USGS Logo Geological Survey Bulletin 1229
Geology of the Circle Cliffs Area, Garfield and Kane Counties, Utah
STRATIGRAPHIC SECTIONS

The stratigraphic sections measured or otherwise described and calculated during this survey are listed in the following tabulation. Sections of the San Rafael Group at Bitter Spring in Hall Creek Valley, sec. 29, T. 33 S., R. 8 E., and of the Morrison Formation at "The Post," lat 37°50' N., long 110°58' W., are not included, as they are available in the report by Craig, Holmes, Freeman, Mullens, and others (1959).

List of stratigraphic sections

Section No. Formation Locality Latitude Longitude
1 Kaibab Limestone and Cutler Formation. White Canyon 37°53'00"111°09'10"
2 Kaibab Limestone and Cutler Formation. East-central Circle Cliffs 37°45'110°00'
3 Kaibab Limestone and Cutler Formation. East-central Circle Cliffs 37°47'30"110°01'00"
4 Kaibab Limestone and Cutler Formation. Central Circle Cliffs, North Fork Creek. 37°47'110°05'30"
5 Cutler Formation, Kaibab Limestone, and Moenkopi Formation. East-central Circle Cliffs, near Burr Trail. 37°50'20"111°02'30"
6 Moenkopi Formation East-central Circle Cliffs, south of Rainy Day mine. 37°46'110°01'
7 Moenkopi Formation Horse Canyon 37°56'00"111°12'
8 Chinle Formation Horse Canyon 37°57'111°13'
9 Chinle Formation Silver Falls Canyon 37°44'111°07'
10 Chinle Formation East-central Circle Cliffs, Burr Trail. 37°50'10"111°02'10"
11 Chinle Formation Deer Point 37°42'00"111°57'00"
12 Glen Canyon Group Canyon 2 miles NE of Deer Point. 37°44'30"1110°57'30"
13 Glen Canyon Group Burr Trail 37°51'111°02'
14 Kayenta Formation Northwest Circle Cliffs, sec. 1 T. 33 S., R. 5 E.
15 Kayenta Formation Silver Falls Canyon 37°40'30"111°12'
16 San Rafael Group 2 miles northwest of Bitter Creek Divide, Rail Creek. 37°59'30"111°05'
17 San Rafael Group Red Slide 37°42'110°56'30"
18 Morrison Formation Long Canyon 37°40'110°53'
19 Morrison Formation Big Thomson Mesa 37°43'110°56'
20 Dakota Sandstone The Post 37°50'110°58'20"







SECTION 1—Kaibab Limestone and Cutler Formation
[In White Canyon, 2 miles northwest of Stud Horse Peaks, north-central Circle Cliffs area, Garfield County; lat 37°53'00" long 111°9'10". Measured by E. S. Davidson]

Thickness
(ft)
Moenkopi Formation (incomplete):

Base of Sinbad Limestone Member of Moenkopi Formation.

Erosional unconformity.

Basal unit of Moenkopi Formation:

Sandstone, white, dolomitic, fine-grained; contains abundant bedded white to gray chert in 1- to 2-in.-thick bands9.3

Sandstone, white, fine-grained; contains as much as 30 percent fragments of white to gray chert3.0

Sandstone, white, fine-grained; contains as much as 50 percent bedded white to gray chert5.0


Total basal unit of Moenkopi Formation17.3
Erosional unconformity.
Kaibab Limestone:

Dolomite, light-yellow, dense; beds 1-2 ft thick; contains moderately abundant gastropod fragments, sponge spicules, specks of glauconite and collophane, some chert nodules and quartz geodes and a few 1- to 2-in.-thick layers of light-green glauconitic dolomitic fine-grained sandstone33.4

Dolomite, light-yellow; contains abundant fine quartz grains and bedded and fragmental gray and white chert, some fine-grained glauconitic sandstone. Unit is poorly exposed4.8

Dolomite, light-yellow; beds 2 ft thick; contains few scattered specks of glauconite quartz geodes in some beds; 2-ft-thick bed at base is a coquina of pelecypod, gastropod, and bryozoan fragments and sponge spicules, some replaced by collophane21.6

Dolomite, light-yellow; contains as much as 20 percent fine to coarse grains of quartz, some pebbles of fine-grained sandstone, and some specks of glauconite.8

Total Kaibab Limestone60.6
Cutler Formation:

White Rim Sandstone Member—upper unit:

Sandstone, light-yellow to light-brown, beds 1-2 ft thick, poorly sorted, fine- to medium-grained; dolomite cement6.4

Dolomite, light-yellow, thick-bedded; contains fragments of gastropods and pelecypods and some fine to medium quartz grains7.0

Sandstone, white, horizontally stratified, thin- to thick-bedded, fine- to medium-grained; some dolomite cement21.6

Sandstone, light-yellow, dolomitic, horizontally stratified, thin-bedded, poorly sorted, medium-grained10.8

Sandstone, white to gray, horizontally stratified, thin-bedded, friable, fine- to medium-grained41.6

Dolomite, light-yellow; contains as much as 25 percent fine grains of quartz, moderate amounts of pelecypod and gastropod fragments, and few subrounded to angular pebbles of black chert2.0

Sandstone, light-yellow to white, horizontally stratified, thin-bedded, poorly sorted, fine- to coarse-grained; some dolomite cement5.4

Sandstone, white, thick-bedded, small- to large-scale trough-type crossbedded, friable, fine-grained; contains some medium to coarse grains of quartz; gradational with underlying unit32.4

Sandstone, white, horizontally stratified, thick-bedded, friable, fine-grained; gradational with underlying unit16.2

Sandstone, white, medium- and large-scale crossbedded in beds as much as 15 ft long, friable, fine-grained10.8

Total exposed upper unit of White Rim Sandstone Member of Cutler Formation154.2


SECTION 2—Kaibab Limestone and Cutler Formation
[In NW cor. sec. 23 (unsurveyed), T. 35 S., R. 8 E., east-central Circle Cliffs area, Garfield County; lat 37°45' long 110°00' Measured by E. S. Davidson and Gilbert Thomas]

Thickness
(ft)
Moenkopi Formation (incomplete):

Conglomerate; consists of 1/4- to 2-in., fragments of chert in a matrix of brown fine-grained sandstone containing as much as 5 percent medium sand; very thin bedded to thin bedded, probably equivalent to Sinbad Limestone Member3.0
Erosional unconformity.
Kaibab Limestone:

Dolomite, cherty, dark-yellow-brown; contains sponge spicules, as much as 5 percent chert fragments, 1-2 percent quartz geodes, as much as 5 percent specks of green apatite, and less than 1 percent hematite nodules; unit is moderately porous7.1

Dolomite, pale-yellow; contains as much as 10 percent fine quartz sand and 20 percent small chert nodules, abundant quartz-geodes, and less than 1 percent specks of green apatite10.2

Dolomite, pale-yellow to white, fine- to medium-grained; contains sponge spicules; beds 1-2 ft thick23.9

Dolomite, pale-yellow-white, fine-grained; contains less than 1 percent medium to coarse grains of quartz and quartz-filled geodes, abundant specks of green apatite; fossiliferous (gastropods) 2.0

Total Kaibab Limestone43.2
Cutler Formation:

White Rim Sandstone Member—upper unit:

Sandstone, dolomitic, fine-grained to very coarse grained, poorly sorted; contains less than 1 percent 3/4- to 2-in., quartz-filled geodes2.6

Sandstone, gray to white, fine-grained, friable, slightly dolomitic at top3.0

Dolomite, pale-yellow to yellow-brown, fine-grained, porous; beds 4 ft thick; locally composed of as much as 80 percent quartz grains20.0

Covered, probably dolomite2.0

Sandstone, fine-grained, well-sorted, friable; blocky beds 2-4 ft thick; contact covered12.7

Sandstone, gray-white, fine- to coarse-grained, poorly sorted, slightly dolomitic, thick-bedded8.3

Sandstone, dolomitic, pale-yellow, fine- to medium-grained; contains as much as 50 percent carbonate and less than 1 percent hematite nodules6.0

Sandstone, white, fine- to medium-grained, poorly sorted; slightly dolomitic2.5

Dolomite, sandy, pale-yellow, fine-grained; contains as much as 30 percent fine to coarse quartz sand and less than 1 percent hematite nodules and traces of petroliferous material2.5

Sandstone, dolomitic, yellow-brown, fine- to medium-grained; contains quartz-filled geodes at base0.5

Sandstone, gray-white, fine- to medium-grained, poorly sorted, friable; horizontally stratified beds 0.5-1 ft thick6.3


Total upper unit66.4

White Rim Sandstone Member—lower unit:

Sandstone, white, fine-grained, friable; composed of clean quartz sand, in planar and trough cross-stratified beds as much as 30 ft long, generally dipping southeast; individual cross-strata 3/4-1 in. thick, sets of cross-strata 8-10 ft thick 108.0

Base of exposure, not base of unit.

Total exposed White Rim Sandstone Member of Cutler Formation174.4


SECTION 3.—Kaibab Limestone and Cutler Formation
[SW1/4 sec. 14, T. 35 S. (unsurveyed), R. 8 E., east-central Circle Cliffs area, Garfield County; lat 37°47'30" long 110°01'00". Measured by E. S. Davidson and Gilbert Thomas]

Thickness
(ft)
Moenkopi Formation (incomplete section):

Conglomerate, poorly sorted; 1/4- to 3/8-in. fragments of white chert in matrix of medium-grained to very coarse grained quartz sandstone with yellowish-orange dolomite cement; petroliferous; probable Sinbad Limestone Member 8.2
Erosional unconformity.
Kaibab Limestone:

Dolomite, light-brown to pale-yellow; contains spicules, less than 1 percent hematite nodules, and a few specks of green apatite 8.4

Dolomite, medium-grained; contains as much as 20 percent fine grains of quartz, abundant nodules of chert, and specks of green apatite; scattered thin parting-plane laminae consist of fine-grained sandstone and green apatite5.2

Dolomite, dense; contains numerous small cavities, abundant sponge spicules, as much as 2 percent specks of green collophane; local layers as much as 1 ft thick contain 1-5 percent quartz geodes; fossiliferous (gastropods)15.6

Sandstone, medium- to coarse-grained, discontinuous; contains abundant specks of green glauconite and collophane .2

Total Kaibab Limestone29.4
Cutler Formation:

White Rim Sandstone Member—upper unit:

Sandstone, white, fine-grained to very fine grained, grades upward into poorly sorted fine- to coarse-grained dolomitic sandstone; unit contains a few quartz geodes5.6

Dolomite, sandy; contains 30-50 percent quartz grains20.5

Sandstone, dolomitic, fine- to coarse-grained; contains as much as 30 percent dolomite; thick-bedded4.6

Sandstone, dolomitic, pale-yellow to gray-white, generally fine grained; contains a few coarse quartz grains; friable; beds 1-4 ft thick; contains as much as 20 percent dolomite19.7

Sandstone, dolomitic, fine-grained to very fine grained; dolomite forms 20-50 percent of unit; contains a few molds of sponge spicules14.2

Sandstone, dolomitic, fine-grained to very coarse grained, poorly sorted, planar cross-stratified in beds 2 ft long1.0

Dolomite, sandy, yellow, thick-bedded; contains as much as 10 percent quartz grains, and specks and globules of petroliferous material4.0

Sandstone, fine- and medium-grained, very thick bedded; contains some sets of planar cross-strata 6 ft long 18.1


Total thickness upper unit87.7

White Rim Sandstone Member—lower unit:

Sandstone, white, fine-grained, friable, in planar sets of southeast dipping cross-strata, individual cross-strata 1-2 in. thick; sets of cross-strata as much as 60 ft long20.0

Base of exposure, not base of unit.

Total exposed White Rim Sandstone Member of Cutler Formation107.7


SECTION 4.—Kaibab Limestone and Cutler Formation
[At North Fork Creak, a tributary of Silver Falls Creek, central Circle Cliffs area, Garfield County; lat 37°47' long 111°05'30". Measured by E. S. Davidson]

Thickness
(ft)
Moenkopi Formation (incomplete section):

Basal unit:

Sandstone, gray to light-yellow, fine-grained, white dolomite cement; contains 25-60 percent gray chert nodules and angular fragments of gray chert, some chert is in beds 2 in. thick and averaging 2 ft in width; contains few quartz geodes with calcite crystals in center, some glauconitic sandy layers, especially near base of unit17.9
Unconformity—sharp erosional contact.
Kaibab Limestone:

Dolomite, light-yellow; horizontally stratified in beds 1-3 ft thick; contains very fine grains of quartz, abundant specks of glauconite and collophane, moderately abundant thin layers of glauconitic sandstone, chert, and quartz geodes; unit is highly fossiliferous (fragments of gastropods, pelecypods, and sponge spicules)23.8

Dolomite, light-yellow, horizontally stratified in beds 1 to 2 ft thick; locally oolitic (1 mm or less); contains some layered budded chert in upper 3 in.; fossiliferous (gastropod, bryozoan stems, sponge spicules); abundant specks of collophane and glauconite16.6

Dolomite, light-yellow; contains as much as 5 percent medium grains of well-rounded quartz, 1 percent specks of collophane, trace quartz crystal lined geodes averaging 1 in. in diameter; fossiliferous (gastropods, bryozoan stems, sponge spicules)2.5

Total Kaibab Limestone42.9
Cutler Formation:

White Rim Sandstone Member—upper unit:

Sandstone, white to light-yellow, fine- to medium-grained, friable; some dolomite cement0.2

Sandstone, dolomitic, light-yellow, fine- and medium-grained, crossbedded; beds in sets 1-2 ft long and 1-2 ft thick; individual beds 6 in. thick; rounded quartz grains well cemented with dolomite; weathered surface is spiny4.5

Dolomite, sandy, light-yellow, oolitic; horizontally stratified in beds 2-4 ft thick; contains 20-30 percent fine and medium well-rounded grains of quartz and locally more quartz grains than dolomite; spiny surface on outcrop18.4

Sandstone, light-yellow, poorly sorted fine- and medium-grained; heavily cemented with yellow dolomite; sharp lower contact; transitional with overlying bed2.5

Sandstone, light-gray, fine- and medium-grained, friable; horizontally stratified in beds 1 in.-2 ft thick; splits every 2 or 3 ft, giving a thick-bedded appearance; local stringers of light-yellow heavily dolomite-cemented sandstone; one 2-ft thick yellow dolomite bed 3 ft above base19.0

Dolomite, sandy, very light yellow; weathers gray; contains 20-30 percent fine to medium grains of quartz and a few 6-in.-thick beds of fine-grained white sandstone; spiny surface on weathered outcrop 24.0

Sandstone, white to light-yellow, horizontally stratified, friable, fine- to medium-grained; contains abundant quartz crystal lined geodes in upper 2.5 ft5.0

Total upper unit73.6
White Rim Sandstone Member—lower unit:

Sandstone, white to very light brown; friable, fine-grained with few medium grains of quartz; planar crossbedded laminae 10 ft long; upper contact is sharp erosional break at section locality 3.0

Total exposed White Rim Sandstone Member of Cutler Formation76.6


SECTION 5.—Moenkopi Formation, Kaibab Limestone, and White Rim Sandstone Member of Cutler Formation
[In NE cor. sec. 20 and NW cor. sec. 21, T. 34 S., R. 8 E. (unsurveyed), east-central Circle Cliffs area, Garfield County (near Burr Trail); lat 37°50'20", long 111°02'30". Measured by E. S. Davidson and Gilbert Thomas]

Thickness
(ft)
Chinle Formation (incomplete):

Mottled-siltstone unit:

Lower 3 ft moderate-brown mudstone; contains abundant scattered coarse to very coarse grains of quartz. Next 4 ft mottled white and purple-white fine-grained to very fine grained sandstone containing scattered coarse to very coarse grains of quartz. Upper 2 ft mudstone; weathers yellow brown; contains abundant hematite nodules9.7
Moenkopi Formation:

Mudstone, dark-reddish-brown to reddish-brown, laminated to very thin bedded, shaly; contains local 1-in.-thick lenses of gray very fine grained micaceous sandstones. (This unit locally removed by pre-Chinle erosion).21.6

Siltstone to very fine grained sandstone, reddish-brown to greenish yellow, cuspate ripple marked, in beds 1/2- to 1 in. thick; very micaceous; slightly calcareous2.6

Mudstone, dark-reddish-brown to reddish-brown, shaly, slightly ripple-laminated to horizontally stratified; laminae 1/16-1/8 in. thick; micaceous; contains a resistant ledge of rippled red siltstone 18.9 ft above base of unit32.1

Sandstone, greenish-gray, very fine grained to silty, ripple-laminated; small-scale cross-stratified in beds 1/4-3 in. thick; slightly calcareous4.5

Silty mudstone and mudstone, reddish-brown; upper 2 ft bleached gray white; contains local lenses of shaly greenish-gray micaceous siltstone and very fine grained sandstone; 6-in.-thick beds of greenish-gray calcareous very fine grained sandstone 40.8-45 ft above base; ripple cross-stratification common throughout unit116.2

Mudstone, gray to greenish-gray; weathers light yellow; contains discontinuous lenses of very fine grained sandstone at 5- to 6-ft intervals; petroliferous29.9

Sandstone, greenish-gray, very fine grained, micaceous; yellowish-brown on surface; contains specks of hematite altered from pyrite1.5

Mudstone and siltstone, gray to yellow-brown; weathers pale green to yellow gray; shaly; very thin bedded; unit contains local discontinuous thin lenses of very fine grained sandstone; petroliferous23.0

Sandstone, brown to black; weathers yellow to gray, fine grained to very fine grained; ripple marks in beds 1/8-1/4 in. thick; contains abundant gypsum on bedding and fracture planes; highly petroliferous; forms ledge30.0

Mudstone, gray, shaly; weathers light yellow; contains local very thin to thin beds of fine-grained sandstone; locally contains gypsum along bedding planes and fractures; poorly exposed; contact with unit below gradational17.2

Sandstone, light-yellow to reddish-brown; slabby to shaly; beds as much as 1 ft thick; ripple marks and small-scale cross-stratification; petroliferous; locally contains limonite and hematite nodules and concretions153.2

Sandstone, very pale yellow to white; unit contains as much as 30 percent chert nodules, and abundant quartz geodes. Upper part of unit is fine-grained sandstone containing as much as 10 percent dolomite cement and abundant 1/4-3/8-in. thick beds of chert; locally upper 5 ft contains more than 50 percent bedded chert; petroliferous18.2

Total Moenkopi Formation450.0
Kaibab Limestone:

Dolomite, pale-yellow; beds 1-2 ft thick; contains quartz geodes, sponge spicules, as much as 5 percent green specks of apatite, and 1-to 2-in.-thick beds of chert22.7

Sandstone, gray to white, fine-grained, friable; contains as much as 5 percent quartz geodes and chert nodules1.7

Dolomite, very thick bedded; contains abundant quartz geodes 5.8

Dolomite, pale-yellow to white; contains as much as 5 percent quartz geodes, a moderate number of specks of green apatite, and, in lower 2-3 ft, as much as 5 percent fine quartz sand; petroliferous; contains gastropods and sponge spicules 14.7

Total Kaibab Limestone44.9
Cutler Formation:

White Rim Sandstone Member—upper unit:

Sandstone, yellowish-gray, fine-grained, well-sorted; friable except in upper 2 ft, which is poorly sorted fine-grained dolomitic sandstone containing as much as 20 percent dolomite; locally petroliferous; fossiliferous (gastropods, pelecypods, and brachiopods) 9.3

Dolomitic sandstone, medium- to coarse-grained, poorly sorted 1.4

Sandstone, gray and white, fine-grained, friable, thin- to thick-bedded 6.9

Sandstone, light-yellow, fine-grained, thick-bedded; cemented with dolomite; base of exposure not base of unit 4.7

Total exposed upper unit of White Rim Sandstone Member of Cutler Formation22.3


SECTION 6.—Moenkopi Formation
[In east-central part of sec. 15, T. 35 S., R. 8 E. (unsurveyed), east-central Circle Cliffs area, Garfield County; lat 37°46' long 111°01' Measured by E. S. Davidson and Gilbert Thomas]

Thickness
(ft)
Chinle Formation:

Mottled-siltstone unit:

Mudstone, mottled light-gray, white, and purplish-brown; contains abundant medium to coarse grains of quartz sand; firmly cemented7.0
Moenkopi Formation:

Mudstone, dark-reddish-brown, micaceous, interbedded with greenish-gray micaceous siltstone to fine-grained sandstone; upper 5 ft purplish brown10.4

Siltstone to very fine grained sandstone, light-greenish-gray, blocky splitting; contains ripple-laminated layers about 1 in. thick2.5

Mudstone, dark-reddish-brown; beds 1/8 in. thick; interbedded with 1/4-in.-thick beds of yellow to greenish-gray very fine grained micaceous sandstone22.8

Sandstone, greenish-gray to yellowish-gray, very fine grained, thin bedded.8

Mudstone, dark-reddish-brown, very thin bedded6.1

Sandstone, light-yellow to greenish-gray, very fine grained, micaceous1.0

Mudstone, dark-reddish-brown, very thin bedded; contains a few interbeds of yellow micaceous very fine grained sandstone2.1

Sandstone to siltstone, yellow to greenish-gray; fine sand to silt; very micaceous; ripple-laminated beds 1/32-4 in. thick4.5

Mudstone, dark-reddish-brown; beds 1/16-1/8 in. thick; contains layers of greenish-gray micaceous very fine grained sandstone about every 3 ft76.4

Siltstone to sandstone, brown, silty to very fine grained, micaceous, probably feldspathic1.6

Mudstone, light-yellowish-gray; upper 8 ft dark reddish brown to brownish red; beds less than 1/16 in. thick; forms slope49.8

Siltstone and fine-grained sandstone, light-greenish-gray, very thin bedded; abundant cuspate ripples; micaceous1.0

Siltstone and mudstone, light-greenish-gray, shaly, pyritic, ripple laminated; beds 1/16-1/8 in. thick15.5

Siltstone, yellowish-gray, ripple laminated; contains less than 0.5 percent pyrite; forms massive ledge2.0

Siltstone, gray; weathers light yellow; shaly; ripple laminated; very thin bedded; contains a few layers of mudstone and less than 0.5 percent pyrite9.0

Siltstone, light-greenish-gray; weathers pale light yellow; contains less than 0.5 percent pyrite cubes1.5

Mudstone, light-gray, slightly micaceous; contains less than 5 percent brownish-red beds; forms slope24.0

Sandstone, brownish-black to black; weathers gray; fine grained; cross stratified; highly pertroliferous; pyritic10.4

Sandstone, dark-gray; weathers light gray; medium grained to very fine grained; contains ripple marks, small-scale cross-strata, and local 1- to 3-ft-thick layers of very thin bedded shaly siltstone; highly petroliferous66.1

Sandstone, dark-gray, very fine grained, thin-bedded, petroliferous; ripple-laminated beds 1/8-1/2 in. thick; ledge former57.2

Siltstone and mudstone, red, thin-bedded to very thick bedded, micaceous10.8

Siltstone, red, ripple-laminated19.1

Sandstone, very fine grained, petroliferous; beds 1-8 ft thick 46.8

Conglomerate, pebbles of chert in a matrix of medium-grained sandstone; cemented by yellowish-orange carbonate; locally petroliferous; probably Sinbad Limestone Member5.2

Total Moenkopi Formation446.6
Kaibab Limestone:

Dolomite, cherty, dark-yellow-brown (not measured).


SECTION 7.—Lampstand Draw section A
[Sec. 13, T. 33 S., E. 6 E. (unsurveyed), northwest Circle Cliffs area. Lat 37°56'00" long 111°12' Section begins 1-1/4 mile up the creek from place where the Long Canyon—The Peaks road crosses Horse Canyon, then transfers 1/2 mile up creek and continues to promontory to west. Measured by J. H. Stewart and G. A. Williams]

Thickness
(ft)
Shinarump Member of Chinle Formation:

Sandstone, pale-greenish-yellow; weathers moderate reddish orange; very coarse grained; poorly sorted (not measured).
Moenkopi Formation:

Claystone and siltstone, grayish-red and pale-reddish-brown; weathers moderate reddish orange and pale reddish brown; upper 3 ft bleached to dark yellowish orange; micaceous; firmly cemented; calcareous; very thinly laminated to thin bedded; papery to slabby splitting; weathers to form steep frothy slope; upper 73 ft forms vertical cliff in which ripple-laminated and pseudo-cross-laminated siltstone is common; thin laminae of siltstone are pale greenish yellow and form conspicuous color bands295.0

Siltstone and claystone, pale-reddish-brown and grayish-orange; weathers pale reddish brown; firmly cemented; calcareous; predominantly shaly splitting with minor flaggy and slabby splitting; abundant ripple marks; weathers to ledges and slopes; contains many lenticular siltstones which form benches and which are current-ripple-laminated with common pseudo-cross-laminations; ledges smaller than in underlying unit158.6

Siltstone and claystone. Siltstone is pale yellowish orange and pale reddish brown (weathers same) and very fine grained, has limonite spots, is firmly cemented (calcareous), forms lenticular ledges, is current-ripple-laminated with common pseudo-crosslamination, is shaly to blocky splitting, and weathers to discontinuous ledges. Claystone is grayish red (weathers same) and micaceous, has very thin current-ripple laminae, is papery to shaly splitting, and weathers to steep rubbly slope. Basal 5-10 ft of entire unit altered to moderate yellow; color change crosses stratification. Unit forms steep ledgy slope91.8

Sinbad Limestone Member:

Dolomite, pale-olive, grayish-yellow, and grayish-olive; weathers dusky yellow; dense to fine grained; contains sparse medium sized crystals; well-cemented; thin parallel laminae to thin parallel beds; sparse thin medium-scale trough and planar sets of high-angle cross-laminations; platy to blocky weathering; weathers to form steep ledgy slope or vertical cliff; abundant poorly preserved fossils, mostly pelecypods; sparse thin to thick sets of laminae of moderate-yellow interbedded siltstone. Section transferred 1/2 mile north on top of this unit44.3

Siltstone and dolomite in lenticular units. Siltstone is moderate yellow and dark yellowish orange (weathers same), is firmly cemented, argillaceous, and thinly laminated to parallel-laminated, and has shaly splitting. Dolomite is grayish yellow (weathers grayish-orange) dense, very thin to thin parallel bedded, and flaggy to blocky splitting. Units weather to form a reentrant or steep rubble-covered slope. Locally the units are absent. They are separated from Kaibab dolomite by an erosion surface which locally shows 5-10 ft of relief7.9

Total Moenkopi Formation597.6
Unconformity.
Kaibab Limestone:

Dolomite, pale-greenish-yellow (not measured).


SECTION 8.—Lampstand Draw section B
[Sec. 3, T. 33 S., R. 6 E. (unsurveyed), northwest Circle Cliffs area, Garfield County; lat 37°57' long 111°13' Section is on promontory about 1-5/8 mile N. 65° W. of top of Lampstand Draw section A. Measured by J. H. Stewart and G. A. Williams]

Thickness
(ft)
Wingate Sandstone (incomplete):

Top of section, not top of outcrop.

Sandstone, very pale orange; weathers pale yellowish orange; very fine grained; well sorted (not measured).
Chinle Formation:

Owl Rock Member:

Claystone and siltstone, pale-reddish-brown and minor pale-olive; weathers pale reddish brown; firmly cemented, slightly calcareous; bedding concealed; tabular; weathers to form steep loose slope; limy siltstone or limestone ledges 9 and 14 ft above base; siltstone ledges 27 and 14 ft below top that do not persist laterally; contains no pure limestone84.7

Sandstone, pale-reddish-brown with blotches of light-greenish gray; weathers pale reddish brown; fine grained; moderately sorted; composed of angular clear quartz and abundant orange accessory minerals; firmly cemented, slightly calcareous; tabular; contains small-scale planar sets of cross-laminae and parallel laminae; platy splitting; weathers to form inconspicuous ledge in steep slope 10.1

Siltstone and claystone, pale-reddish-brown and minor light-greenish-gray; weathers pale reddish brown; firmly cemented, calcareous and argillaceous; bedding concealed; weathers to form steep loose slope; limy siltstone in 3-ft-thick bed at 65.8 ft above base, and in 2-ft-thick bed at 73.2 ft 86.4


Total Owl Rock Member181.2

Petrified Forest Member:

Sandstone, grayish-purple, light-greenish-gray, and grayish-red; weathers pale red purple and very pale orange; medium grained, moderately sorted; composed of subangular clear quartz and abundant orange and black accessory minerals; weakly cemented, calcareous; tabular; small- to medium-scale trough sets of cross-laminae; shaly to slabby splitting; weathers to form steep vertical cliff with steep rubbly slope below 39.2

Siltstone, predominantly pale-reddish-brown with minor greenish-gray mostly confined to lower part; weathers moderate red; contains sparse to abundant medium to coarse sand grains; composed of clear quartz and black and orange accessory minerals; firmly cemented, calcareous; bedding concealed; weathers to form steep rubbly slope; variegated in color; medium- to fine-grained sandstone beds as much as 4 in. thick at several levels; near base of unit, a very thin bed of granule conglomerate contains sparse pebbles 83.4

Sandstone, predominantly dusky red, minor light greenish-gray; weathers moderate yellowish brown; medium grained; moderately sorted; composed of subangular clear quartz and abundant orange and black accessory minerals; poorly cemented, calcareous; tabular; large-scale planar and trough sets of cross-laminae; minor ripple laminae; splitting obscure; weathers to form steep bare-rock slope; light greenish gray confined to very thin beds at 3-ft intervals between sets of cross-laminae and occasionally in cross-laminations. 12.8

Claystone, pale-reddish-brown, dusky-red, and grayish-red-purple; weathers same; firmly cemented, argillaceous; stratification concealed; weathers to form steep frothy slope; white bleached spots and nodules contain fragments of the surrounding clay 51.2

Total Petrified Forest Member186.6

Monitor Butte Member:

Claystone, predominantly greenish-gray; some variegated brownish gray and dark reddish brown with greater amount of dark reddish brown near top; weathers to light greenish gray; firmly cemented, calcareous and argillaceous; contains sparse siltstone, sandstone, and conglomerate beds which extend only short distances and are grayish red, very dusky red purple, and pale green. Conglomerate beds composed of limestone pebbles. Siltstones and sandstones highly micaceous, current ripple-laminated, commonly pseudo-cross-laminated, and shaly to slabby splitting. Entire unit weathers to form steep frothy slope and minor ledges129.6

Siltstone and sandstone interbedded, pale-reddish-brown; very pale green in sandy ledges; weathers pale reddish brown. Sandstone is very fine grained, is composed of clear quartz, and contains common mica flakes and abundant limonite spots. Unit firmly cemented, calcareous, lenticular; bedding mostly concealed, but ledges current ripple-laminated and sparsely pseudo-cross-laminated. Shaly to blocky; weathers to form steep rubbly slope32.4

Claystone and siltstone, light-bluish-gray and medium-bluish-gray; lower 5 ft pale yellowish orange; weathers light bluish gray; commonly contains mica flakes; firmly cemented, calcareous and argillaceous; lenticular; bedding in claystone concealed; siltstone forms lenticular beds as much as 4 ft thick throughout unit; shows current ripple lamination and common pseudo-cross-lamination; at many places beds dip at gentle angles from regional dip; shaly to blocky splitting; entire unit weathers to a steep frothy and rubbly slope; sandstones of the Shinarump Member interfinger with this unit laterally37.8

Total Monitor Butte Member199.8

Mottled-siltstone unit:

Claystone and siltstone, grayish-red and pale-reddish-brown; weathers pale reddish brown; firmly cemented, calcareous; bedding in claystone concealed, siltstone current ripple-laminated; common pseudo-cross-lamination, shaly to flaggy splitting; weathers to form steep slope and minor ledges. Siltstone from 7.4 ft to 12.3 ft, pale yellowish orange in lower part and grayish purple in upper part; contains very coarse grains of subrounded clear quartz and orange accessory minerals; manganese nodules19.2

Total Chinle Formation586.8
Moenkopi Formation:

Claystone and siltstone, grayish-red and pale-reddish-brown (not measured).


SECTION 9.—Silver Falls section B
[Secs. 25 and 26, T. 35 S., R. 7 E. (unsurveyed), lat 37°44' long 111°07' at southwest side of the farthest outlying mesa between Dry Fork and South Fork of Silver Falls Creek. Measured by L. C. Craig, G. A. Williams, H. F. Albee, and J. H. Stewart]

Thickness
(ft)
Wingate Sandstone (incomplete):

Conglomeratic sandstone, grayish-red to pale-greenish-yellow; weathers to pale reddish brown; very coarse grained to fine grained; poorly sorted; well rounded abundant white and black accessory minerals, also yellow and clear quartz; well cemented, argillaceous, very weakly calcareous; tabular to irregular; structureless to faintly parallel structured with small cross-laminated lenses; slabby weathering; contains granules and pebbles as much as 1-in. in diameter, mostly angular and composed of gray chert; basal contact bevels Owl Rock Member disconformably, cutting out as much as 5 ft of beds in 15 ft along contact1.8
Unconformity.
Chinle Formation:

Owl Rock Member:

Same as below but locally weathers to vertical slopes with hoodoo shapes; tabular with medium-scale trough sets of cross-laminae, subparallel laminae, or ripple laminae; common light-greenish-gray circular spots appear to have black, carbonaceous center16.9

Siltstone, pale-red, firmly cemented, highly calcareous; hackly weathering; forms steep rubbly slope broken by 1.5-ft ledge at 45 ft and 3.5-ft ledge at top of unit. Ledges are conglomeratic sandstone that is pale red mottled with light greenish gray and that weathers light brown; composed of reddish and greenish calcareous siltstone pebbles as much as 1-in. in diameter and minor clear quartz, pinkish to white chert granules, and sparse interstitial clear quartz. Unit is tabular, parallel to subparallel bedded, slightly calcareous 66.9

Limestone and siltstone, alternating. Limestone is moderate orange pink and very light gray, weathers pale red with very light gray mottling, is very finely crystalline, has black to red silica-filled stringers, and is tabular; it is thick bedded to very thick bedded and hackly splitting, and weathers into ledges. Siltstone is pale red, light olive gray, and very light gray; weathers pale red; is well sorted; is composed of sparse clear quartz and white mineral; is firmly cemented, calcareous; forms a tabular unit with parallel-laminated sets; is platy to papery and in part hackly; and weathers to steep slope. In ascending order, this unit consists of siltstone, 12.1 ft; limestone, 2.8 ft; siltstone, 15.9 ft; limestone, 5.0 ft; siltstone, 12.6 ft; limestone, 6.0 ft; siltstone, 7.9 ft; limestone, 5.3 ft; siltstone, 4.5 ft; and limestone, 5.9 ft78.0

Total Owl Rock Member161.8

Petrified Forest Member:

Claystone, pale-reddish-brown, pale-red, and light-brown, silty; hackly weathering; forms steep earthy to fine-rubble-covered slope; contains light-gray granule nodules about 20 ft above base; entire unit forms pinkish faintly banded interval on distant cliffs60.6

Sandstone and siltstone, pale-red, pale-brown, pale-reddish-brown, and very dusky red purple; where sand is coarse, very light gray; well sorted; composed of rounded clear quartz grains and common pink and black accessory minerals; firmly to weakly cemented, calcareous; sandstone is tabular with lenticles of medium-scale trough crossbed sets; most cross-strata alternately light gray and very dusky red purple; hackly fracture; weathers to a steep slope42.4

Claystone, pale-reddish-brown to light-brown to pale-red; middle mottled light greenish gray to moderate yellowish brown, highly silty to very fine grained sandy; hackly fracture; weathers to shallow frothy surface; entire unit poorly exposed74.2

Claystone; pale red purple to grayish red purple in lower third, pale reddish brown in middle third, and pale red in upper third; slightly silty lower third and upper third, highly silty middle third; hackly fracture when fresh; weathers to a deep frothy surface; at top is 6-in. layer of white fine- to medium-grained poorly sorted sandstone composed of clear quartz with abundant red, green, and black accessory minerals and sparse biotite flakes; tabular; small-scale trough sets of cross-laminae; sandstone forms indistinct ledge capping steep badland slope on claystone; unit forms prominent brightly colored band above gray Monitor Butte Member; lower half of unit contains abundant granule- to boulder-sized limestone nodules 177.4

Total Petrified Forest Member354.6

Monitor Butte Member:

Alternating sandstone and siltstone. Sandstone is light brown to grayish yellow, weathers light brownish gray, is fine grained to very fine grained, and moderately sorted, is composed of clear quartz, common black minerals, sparse to common biotite flakes, and interstitial limonite(?), is firmly cemented and calcareous; sandstone units are lenticular and have thin to very thin sets of ripple laminae and cross-laminae. Siltstone is light olive gray, weathers light gray, is poorly cemented and calcareous; it is thinly laminated and irregular splitting; weathers to gentle slope. At the base of the unit, a thin lenticular conglomerate contains pebbles as much as 3/4-in. in diameter and composed predominantly of limestone; sandstone lenses are at 7.3 ft, 21.2 ft, 27.5 ft, and 31.8 ft; between 33.8 ft and 37.1 ft, sandstone lenses predominate; each sandstone lens has a different attitude, possibly representing contorted bedding37.1

Silty claystone, pale-green to medium-light-gray; weathers light gray; well-sorted; composition masked; poorly cemented, calcareous; tabular; shaly; weathers to a steep slope; expands slightly when wet (bentonitic?); contains rounded limonite concretions as much as 4-in. in diameter; unit contains several prominent steeply dipping sandstone beds in lower 20 ft (foresets?)157.2

Total Monitor Butte Member194.3

Shinarump Member:

Sandstone, grayish-yellow to moderate-yellow; weathers to brownish black; predominantly coarse grained with minor very coarse grains; poorly sorted; composed of subangular clear quartz and rare black grains; brown-stained interstitial clay; clay binding, slightly calcareous; lenticular unit of medium-scale trough sets of cross-laminae, slabby to platy, forms thin capping ledge that pinches out 25 ft southwest but swells to 40 ft thick 1/4 mi northeast1.8

Total Chinle Formation712.5
HR>
Unconformity: Sharp scour contact.
Moenkopi Formation (not measured).


SECTION 10.—Chinle Formation
[In south-central part of sec. 16, T. 34 S., R. 8 E. (unsurveyed), in east-central Circle Cliffs area, Garfield County; on southeast side of Burr Trail; lat 37°50'10" long 111°02'10" Measured by E. S. Davidson and Gilbert Thomas]

Thickness
(ft)
Wingate Sandstone (incomplete):

Sandstone, fine-grained, slightly friable, subrounded to subangular grains, well-sorted; contains local layers of well-rounded medium to coarse grains of quartz; lower 4 ft contains abundant medium to coarse grains of quartz and lower 0.6 ft contains thin beds of coarse grained sandstone 80.6
Chinle Formation:

Owl Rock Member:

Sandstone, grayish-purple with local greenish-gray streaks and splotches, fine-grained, ripple-laminated, massive splitting; contains abundant mica and an unidentified green mineral that may be chlorite or epidote, interstitial white clay (may be what is referred to locally as the so-called Hite Bed of Church Rock Member) 6.6

Mudstone, reddish-brown, slickensided; contains scattered chert pebbles.9

Sandstone, light-reddish-brown, very fine grained with a few scattered medium grains of quartz, slightly dolomitic; lower 1 ft is conglomerate composed of gray chert pebbles in poorly sorted fine-grained sandstone matrix4.3

Siltstone to sandstone, pale-red-purple; composed of silt to very fine sand, crossbedded2.2

Conglomerate; small pebbles of chert and siltstone in a matrix of moderate-brown mudstone.4

Mudstone, moderate-brown with a few greenish spots, very thinly bedded38.6

Conglomerate, reddish-brown mottled greenish-gray; contains well-rounded fragments of reddish-brown mudstone and gray siltstone as much as 1 in. in diameter; matrix of dolomitic fine- to medium-grained sandstone1.1

Mudstone, moderate-brown with a few greenish-gray specks9.9

Dolomite, greenish-gray; contains a few gray chert nodules1.9

Sandstone and siltstone, mottled reddish-brown and greenish-gray; consists of silt to very fine sand; slightly dolomitic in lower 6 ft, grading upward into moderate-brown thinly laminated mudstone 17.8

Limestone, mottled reddish-brown and greenish-gray; contains as much as 50 percent fragments of greenish-gray dolomite in lower 3 ft; a few rounded nodules of greenish-gray and gray chert; fracture surfaces are coated with finely crystalline dolomite 5.2

Mudstone, mottled greenish-gray and brown; weathers light yellowish brown; contains local lenses of limy mudstone 44.0

Limestone (dolomite?) mottled greenish-gray and red; contains a few chert pebbles and abundant resistant limy nodules; massive; hackly fractures7.1

Mudstone, reddish-brown mottled greenish-gray; contains a 3-ft bed of siltstone 7.4 ft above base 48.6

Limestone, light-brownish-gray mottled greenish-gray, fine-grained, blocky, probably dolomitic 2.8

Mudstone, mottled green and reddish-brown; displays slickensided surfaces2.3

Limestone, greenish-gray, dense, thick-bedded; contains as much as 10 percent white chert nodules 1/16- to 1/2-in. in diameter and a few limy concretions with hematite borders 2.1

Sandstone, light-brown; weathers lighter; fine grained and very fine grained; contains much silt; slightly bentonitic; grades upward into light-brown mudstone which is mottled bluish-green in upper loft of unit60.9

Total Owl Rock Member256.7

Petrified Forest Member:

Sandstone, fine-grained, lenticular, blocky fracturing; contains as much as 10 percent interstitial white clay and a trace of green chlorite(?), abundant muscovite on parting planes, and brownish-black biotite(?)0.8

Sandstone, moderate-brown with abundant greenish-gray splotches, very fine grained, silty, thinly laminated to slightly ripple laminated; contains local lenses a few inches thick of thinly laminated greenish-gray sandstone; unit is bentonitic, feldspathic; contains moderate amounts of green chlorite(?) and brown biotite28.7

Sandstone, gray-white to grayish-purple and white, medium grained, well-sorted, planar and trough crossbedded; contains local layers of variegated bentonitic sandstone; kaolinitic; contains abundant greenish flakes of chlorite(?) and greenish-brown flakes of biotite(?); weathers to rounded forms20.7

Conglomerate; contains banded grayish-purple and gray-white medium- to coarse-grained quartz sandstone, fragments of purplish- and greenish-gray mudstone and pebbles of reddish brown siltstone, in matrix of bentonitic grayish-purple and white siltstone3.4

Mudstone, pink to pale-red-purple, bentonitic35.0

Mudstone, light-brown, bentonitic; poorly exposed17.7

Mudstone, grayish-purple to grayish-purple and white; contains abundant flakes of gypsum and dense nodules of limestone; bentonitic9.8

Covered interval, probably same as overlying unit4.0

Mudstone, reddish-brown; bentonitic; contains local lenses of poorly sorted medium-grained kaolinitic sandstone, scattered nodules of chert, fragments of petrified wood, and gypsum flakes on slope 32.4


Total Petrified Forest Member152.5

Monitor Butte Member:

Mudstone, gray, bentonitic, micaceous5.2

Covered; probably medium-grained gray kaolinitic sandstone containing abundant micas, and traces of malachite as coating on fractures and bedding planes, conglomeratic at base5.4

Mudstone, grayish-purple, bentonitic; contains 1-ft layer of gray calcareous chert nodules37.8

Mudstone, variegated reddish-brown, brown and grayish-purple, bentonitic108.0

Total Monitor Butte Member156.4

Mottled-siltstone unit:

Sandstone, mottled grayish-purple and white, fine-grained to very fine grained; contains scattered coarse quartz grains6.0

Total Chinle Formation571.6
Moenkopi Formation:

Mudstone and siltstone, reddish-brown thin-bedded (not measured).


SECTION 11.—Chinle Formation
[Southeast Circle Cliffs area, east of Deer Point; lat 37°42'00" long 110°57'00", Measured by E. S. Davidson and Albert Specht]

Thickness
(ft)
Wingate Sandstone:

Sandstone, light-brown, fine-grained with abundant well-rounded coarse grains of quartz; large-scale planar and trough cross-stratified (not measured).
Chinle Formation:

Owl Rock Member:

Limestone, light-purple; increasing amount of claystone toward base of unit2.5

Siltstone and mudstone, purple-brown, thinly laminated22.5

Sandstone, light-greenish-gray; weathers brown; rippled and small planar type crossbeds; very fine grained; contains local lenses of brown siltstone; ledge forming15.5

Siltstone, brown; contains local lenticles of greenish-gray silty limestone38.7

Limestone, greenish-gray, thin-bedded, silty, slope forming12.9

Siltstone to sandstone, light-gray; weathers light brown; blocky splitting; ripple-laminated; composed of silt to very fine sand; ledge-forming10.5

Mudstone and siltstone, reddish-brown and greenish-gray, poorly exposed, slope-forming16.2

Limestone, greenish-gray, ledge-forming5.0

Mudstone and siltstone, reddish-brown and greenish-gray, slope-forming11.9

Pebble conglomerate, light-greenish-gray; consists of medium- to coarse-grained sandstone matrix and pebbles of greenish-gray limestone; grades into underlying unit1.0

Mudstone and siltstone, reddish-brown and greenish-gray, very calcareous in upper 6 ft, poorly exposed, slope-forming70.8

Limestone, greenish-gray with red streaks, medium crystalline; contains some interbeds of greenish-gray mudstone in lower 4 ft12.9

Mudstone, light-brown to light-grayish-purple, calcareous; contains local lenses of purplish and light-greenish-gray limestone15.7

Limestone, light-greenish-gray, finely crystalline with abundant coarse crystals of calcite and coarse grains of quartz4.0

Mudstone, light-brownish-red, very slightly bentonitic28.2


Total Owl Rock Member268.3

Petrified Forest Member:

Mudstone, variegated hues of purple, brownish-red, and yellow, bentonitic56.4

Sandstone and pebble conglomerate, reddish-brown, medium- to coarse-grained arkosic sandstone; contains pebbles of brown limestone7.0

Mudstone, variegated purple and reddish-brown, bentonitic; sandy at top29.2

Mudstone, brownish-orange, bentonitic38.6

Mudstone, variegated purple, pale-red-purple, yellow, bluish-gray, bentonitic, lenses of brown sandstone in upper 10-ft32.9

Claystone to mudstone, reddish-brown, bentonitic; contains abundant masses of nodular calcareous concretions in upper 15-ft and lenses of purplish-gray medium-grained calcareous sandstone in upper 10-ft; abundant chips and flakes of fibrous limy gypsum on surface of outcrop56.4

Total Petrified Forest Member220.5

Monitor Butte Member:

Sandstone, gray to dark-brown, thick-bedded, ripple-laminated and small-scale crossbedded, fine- and medium-grained; few thin beds of interlaminated brown mudstone and brown fine grained sandstone; 100-ft to south this unit interfingers with overlying bentonitic mudstone6.6

Conglomerate, gray; medium- to coarse-grained matrix of quartz and limestone; pebbles of limestone and siltstone average 1/2 in. in diameter; maximum size 3 in.; calcite cement; some interstitial white clay2.0

Mudstone and claystone, variegated blue-green, bluish-gray and purple; local beds of limestone in globular masses; some lenses of gray to white sandstone; some fissures flied with calcite crystals89.4

Sandstone and mudstone, brown, thin-bedded and ripple-laminated, fine- and medium-grained, feldspathic. Mudstone is gray and finely laminated4.8

Sandstone, grayish-white, thick-bedded, ripple-laminated and small-scale crossbedded, fine- and medium-grained; contains some greenish-gray clay partings, a few greenish-gray clay balls9.5

Sandstone and shale, black and white; interbedded medium grained kaolinitic sandstone and very carbonaceous gray to black shale.3

Total Monitor Butte Member112.6

Total Chinle Formation601.4
Moenkopi Formation (incomplete):

Siltstone, brown, ripple laminated, ledge-forming6.0

Base of section, not base of exposure.


SECTION 12.—Glen Canyon Group
[In east-central Circle Cliffs area; lat 37°44'30", long 110°57'30". Measured by E. S. Davidson and Albert Specht]

Thickness
(ft)
Carmel Formation (incomplete):

Silt and shale, moderate red to moderate reddish-brown (not measured). Sandstone, brown, flat-bedded, poorly sorted, fine grained to very coarse grained5.0
Navajo Sandstone (measured by planetable and graphic methods):

Sandstone, white, fine-grained, friable, quartzose with a few scattered dark minerals; large-scale crossbedded; beds as much as 200 ft long and in sets 50 ft thick; smaller in upper 100 ft of unit; numerous carbonate-cemented fissures in upper part of unit, increasing in quantity upward; a few calcareous sandstone beds separate the sets of cross-strata 150-600 ft below top; average spacing of parting planes in middle 800 ft of unit is almost 100 ft; spacing of parting planes in lowest 100 ft is 5-25 ft; some parting planes in lowest 100 ft marked by brown calcareous sandstone1,036.0
Kayenta Formation:

Sandstone, reddish-brown, massive; small-scale trough crossbedded; fine-grained; some gray and greenish-gray mudstone chips 6.6

Sandstone, light-gray; weathers light brownish red; very thick bedded; flaggy-splitting; medium and coarse grained; abundant gray and brown mudstone chips; small-scale trough crossbedded insets 6-8 ft long83.6

Sandstone, white, massive, friable, very large scale planar and trough cross-stratified with local beds of small-scale trough cross-strata sets; sharp erosional contact with overlying unit30.8

Sandstone, brown, thin- to thick-bedded, medium-grained, small-scale trough crossbedded; abundant brown mudstone chips, lenses of very coarse sandstone with abundant mudstone chips; sandstone is feldspathic and slightly micaceous22.0

Sandstone, white, very thick bedded, friable, fine- and medium-grained, quartzose; small- and medium-scale planar and trough crossbedded 41.6

Sandstone, brown to brownish-red, arkosic, thick-bedded, flaggy splitting, horizontally stratified and small-scale trough cross-stratified; medium grained, local concentrations of coarse and very coarse quartz grains at base 92.4

Total Kayenta Formation277.0
Wingate Sandstone (measured by planetable and graphic methods):

Sandstone, light-brownish-orange, very large scale planar and trough crossbedded, well-sorted, very fine-grained to fine-grained with a few coarse grains of quartz; sharp contact with overlying Kayenta Formation; few lenticles of calcareous sandstone that weather into lacy structures, especially in upper half of unit225.0

Sandstone, white, small-scale trough and planar crossbedded, fine-grained, friable; sharp contact with underlying Chinle Formation8.0

Total Wingate Sandstone233.0
Chinle Formation (incomplete):

Owl Rock Member (incomplete):

Limestone, purplish-gray3.0

Mudstone, reddish-brown (not measured).

Base of section, not base of exposure.


SECTION 13.—Glen Canyon Group
[At Burr Trail, midwestern part of sec. 15, T. 34 S., R. 8 E., Circle Cliffs area, Garfield County; lat 37°51', long 111°02' Navajo and Wingate Sandstone measured by planetable method; Kayenta Formation measured on ridge 1,000 ft southeast of Burr Trail in Muley Twist Canyon. Measured by E. S. Davidson and Gilbert Thomas]

Thickness
(ft)
Carmel Formation (incomplete):

Sandstone, brown, coarse-grained6-8
Navajo Sandstone:

Sandstone, white, poorly sorted1.0

Sandstone, white, very fine grained to fine-grained, well-sorted, cross-stratified; cemented by calcium carbonate; in upper 100 ft cross-stratified trough sets are 40-50 ft long; throughout rest of unit cross-stratified planar and trough sets are as much as 200 ft long 966.0

Sandstone, white, fine-grained, well-sorted; crossbedded in planar sets 4-8 ft thick10.0

Sandstone, greenish-gray, fine-grained; contains abundant coarse quartz grains, some interstitial green clay1.0

Total Navajo Sandstone978.0
Kayenta Formation:

Siltstone and mudstone, grayish-red and purple with green streaks perpendicular to the bedding, irregular masses of bleached green rock extending down into unit; contains a few medium-sized quartz grains and a few iron-oxide cemented nodules of siltstone with limonitic centers1.7

Sandstone, reddish-brown, fine-grained; interbedded ripple-stratified micaceous fine-grained silty sandstone in lenticular units about 1 in. thick12.4

Sandstone, pale-red to pale-red-purple, fine-grained; trough and high-angle planar cross-stratification; trough cross-stratified in sets 10 ft long and 3 ft thick; high-angle planar cross-stratified in sets 0.5-1 ft thick; unit forms ledges and slopes45.0

Sandstone, white, medium-grained, well-sorted; trough cross-stratified in sets 4-5 ft long and 2-3 ft thick10.0

Sandstone, purplish-red, fine-grained, thin-bedded; contains a few ledge-forming beds; upper 6 ft similar to overlying unit10.0

Sandstone, gray, fine-grained; calcareous; rippled and contorted laminar beds; forms small ledges 3.8

Sandstone, pale-red-purple, fine-grained, friable, massive1.3

Sandstone, light-purplish-red; weathers light yellow; fine-grained; well-sorted; planar cross-stratified in sets 4-5 ft thick and 25 ft long17.8

Covered, probably same as underlying unit 5.0

Sandstone, pale-red-purple; weathers yellowish-brown; fine-grained with abundant scattered grains of medium-sized clear and reddish quartz, poorly sorted; planar cross-stratified in sets 10-15 ft long and 3-5 ft thick20.2

Covered. Float indicates siltstone and fine-grained sandstone with local lenses of medium-grained sandstone cemented by carbonate; unit as a whole reddish brown to purplish red, in beds 1/8-1/4 in. thick20.0

Sandstone, fine-grained with some scattered medium grains, poorly sorted, calcareous; high-angle planar cross-stratified; some penecontemporaneous slump bedding 8.5

Sandstone, pale-red-purple, fine-grained; micaceous; beds form ledges 2-6 ft high; unit is ripple cross-stratified and planar cross-stratified in sets as much as 20 ft long; thin bedded; contains discontinuous lenses of calcareous fine-grained white sandstone39.0

Sandstone, white to pale-red-purple, medium- to coarse-grained, abundant 1/2- to 2-in. pebbles of greenish-gray siltstone and mudstone; poorly sorted; trough cross-stratified in sets 2-3 ft long, 1 ft thick; cemented by calcium carbonate1.6

Sandstone, pale-red-purple; weathers brown, fine-grained; planar cross-stratification in sets 30 ft long and 5-6 ft thick; unit forms ledge13.5

Sandstone, pale-red-purple to pale-red, fine-grained, friable, beds 1/8 to 3/8 in. thick; local planar cross-stratified in sets 3 ft long; unit mostly slope forming except for one ledge-forming calcareous sandstone near top47.1

Sandstone, white, fine- to medium-grained, well-sorted; cross-stratified in sets 1 ft thick; lower 2 ft contains abundant green and dark-red dish-brown mudstone chips; carbonate cement 25.0

Mudstone, dark-reddish-brown.7

Sandstone, very light orange, fine-grained, well-sorted, slabby to massive, ripple-stratified and horizontally stratified; beds 1/8 to 1 in. thick forming massive ledges 2-5 ft thick; local trough cross-stratified in sets 1-2 ft thick and 1 ft long; few high-angle planar cross-stratified sets 4 in. thick24.6

Total Kayenta Formation307.2
Wingate Sandstone:

Sandstone, very light brown to brown, very fine grained to fine grained, well-sorted; trough type cross-stratified in sets 40-60 ft thick and 100 ft long; cliff forming; weathers into rounded forms; contains abundant round solution cavities on weathered surfaces232.0
Chinle Formation (reported in section 10).


SECTION 14.—Kayenta Formation
[In SE cor. sec. 1, T. 33 S., R. 5 E., northwest part of Circle Cliffs area, Garfield County Measured by G. A. Miller]

Thickness
(ft)
Navajo Sandstone:

Sandstone, white, large-scale trough and planar cross-stratified, well sorted, very fine grained (not measured).
Kayenta Formation:

Limestone, gray to dusky-red, thin-bedded, sandy3.0

Sandstone, light-gray to moderate-reddish-orange, horizontally stratified, silty, very fine grained, limonite speckled; abundant dark heavy minerals5.0

Covered, float of gray slabby sandy limestone10.0

Sandstone, red and very dark red, very thin bedded to thick-bedded, very fine grained to fine-grained32.0

Sandstone, white, small-scale trough crossbedded, well-sorted, fine-grained to very fine grained 12.0

Mudstone, dusky-red, thinly bedded; contains grains ranging in size from silt to coarse sand, mudstone pebbles1.0

Sandstone, white, large-scale crossbedded, fine-grained to very fine grained; few red mud splits less than 1 ft thick64.0

Sandstone, red to very dark red, very thin bedded, calcareous; fills lows in underlying sandstone unit4.0

Sandstone, white to light-gray, large- and small-scale trough and planar crossbedded, well-sorted, very fine grained36.0

Sandstone, yellow-brown to light-red, thin-bedded to very thin bedded, poorly sorted, silty to fine-grained26.0

Sandstone, orange-red to very dark red, very thick bedded to thick-bedded, poorly sorted, very fine grained to fine-grained38.0

Sandstone, light-red to orange-red, very thin bedded to thin-bedded, silty, very fine grained to fine-grained42.0

Sandstone, light-red to pink-red, massive to trough crossbedded, fine-grained to very fine grained67.0

Total Kayenta Formation340.0
Wingate Sandstone:

Sandstone, light-red to orange, large-scale planar and trough cross bedded, very fine grained to fine-grained (not measured).


SECTION 15.—Kayenta Formation
[Southeast side of Silver Falls Creek Canyon about 1 mile northeast of junction with Escalante River; lat 37°40'30" N., long 111°12' W. Measured by R. F. Wilson and J. R. Gigone]

Thickness
(ft)

Top of section, not top of exposure.
Navajo Sandstone (incomplete):

Sandstone, very light gray and pinkish-gray in basal few feet and moderate-reddish-orange above; weathers same colors; fine grained to very fine grained; sparse scattered medium grains; well sorted; base sharp and even; unit contains a thick set of pale-red limy sandstone containing nodules of white chert 10 ft above base30.0
Kayenta Formation:

Siltstone, pale-reddish-brown in lower two-thirds and greenish-gray in upper third; weathers same colors; medium silt; micaceous firmly cemented; stratification concealed; weathers to form covered slope; base sharp and even 18.1

Sandstone, pale-reddish-brown - weathers pale red; fine-grained, locally very fine grained and medium grained; well to moderately sorted; composed of reddish-stained quartz, light and dark accessory minerals, and mica; firmly cemented; trough and some planar sets of low-angle to very low angle medium- to large-scale cross-laminae and some horizontal laminae; weathers to form ledgy cliff; base sharp and irregular; unit contains scattered clay pellets in lenticular zones 89.2

Sandstone, moderate-orange-pink; weathers light brown, very fine grained to fine grained, well-sorted; composed of frosted pinkish-stained quartz and sparse dark accessory mineral; firmly to poorly cemented; planar sets of medium-scale high-angle cross-laminae; weathers to form vertical cliff; base sharp and even16.2

Silty sandstone to sandy siltstone, pale-reddish-brown to pale-red; weathers same colors; grades from very fine grained sandy siltstone to very fine grained silty sandstone, well-sorted; composed of reddish-stained quartz, a common dark accessory mineral, and mica; poorly to well-cemented; horizontal and wavy laminae; weathers to form slope18.9

Sandstone, grayish-orange-pink, light-brown, pale-red, pale-reddish-brown, and minor moderate-reddish-orange; weathers same colors; fine grained to very fine grained; well sorted; composed of reddish-stained quartz, dark and sparse light accessory minerals, light and dark mica, and common scattered clay pellets; firmly cemented; horizontal laminae and small to large trough sets of small- to large-scale low-angle to very low angle cross-laminae; weathers to form ledgy cliff; base sharp and irregular and marked by scour surfaces; unit contains several clay pellet conglomerate lenses 173.4

Total Kayenta Formation315.8
Wingate Sandstone (incomplete):

Lukachukai Member (incomplete):

Sandstone, light-brown to moderate-reddish-orange; weathers same colors and pale yellowish orange; very fine grained, locally very fine grained to fine grained; well sorted74.8


SECTION 16.—San Rafael Group
[2 miles northwest of Bitter Creek Divide, sec. 25, T. 32 S., R. 7 E., lat. 37°59'30" long. 111°05' Measured by J. C. Wright and D. D. Dickey]

Thickness
(ft)
Morrison Formation (incomplete):

Sandstone, crossbedded; fills channels; abundant chert pebbles in lower 1 foot and in some other layers10.0
NOTE.—The Summerville-Morrison contact is placed at the base of the lowest crossbedded sandstone. The upper 14 ft of the underlying unit is light greenish gray and may be part of Morrison Formation.
Summerville Formation:

Covered, probably red shale and siltstone, upper 14 ft is light greenish gray44.0

Limestone, very light gray, dense, massive; has red cherty blebs1.0

Covered, probably red shale and siltstone17.0

Limestone, very light gray, dense, massive; has red cherty blebs; similar to top of Summerville Formation as defined at Summerville point; forms ledge; appears to be fairly continuous for several hundred yards2.0

Covered, probably red shale and siltstone3.5

Sandstone, very limy, white, very thin to thin, even beds2.5

Covered, probably red shale and siltstone3.0

Sandstone, very limy, white, very thin to thin even beds, ripple laminated at the top of each bed; many layers have conspicuous coarse grains and granules of colored and black chert; forms ledge3.0

Mostly concealed by red wash, probably shale and siltstone; forms slope81.0

Total Summerville Formation157.0
NOTE.—The Summerville-Curtis (?) contact is concealed, probably conformable.
Curtis(?) Formation:

Limestone, very sandy, light-greenish-gray, cherty cement and nodules, thin bedding with reworked appearance; forms small ledge3.0

Total Curtis(?) Formation3.0
NOTE.—The Entrada-Curtis(?) contact shows gentle scours about 6 in. deep in the top of the Entrada; the Curtis(?) appears to contain reworked Entrada Sandstone.
Entrada Sandstone:

Upper sandy member:

Sandstone, light-brown, top 2-12 ft bleached greenish-gray, like Curtis(?) Formation, very fine grained, well-sorted, indistinctly very thin bedded to massive, some irregular flat bedding in unit; 150 yds north of the section a white slickrim sandstone with large-scale crossbedding occupies part of this interval; slickrim thickens northward from 25 ft to 60 ft in 100 yds by addition to the base of the sandstone; the top contact maintains an even interval of 38 ft below the base of the Curtis(?)55.0

Siltstone, reddish-orange, earthy, poorly exposed; much of it in beds 5-15 ft thick; purple clay partings; lower 15 ft shows some light-greenish-gray mottling153.0

Sandstone, light-greenish-gray, fine-grained, poorly to moderately cemented; composed of white well-rounded quartz grains and some light-red grains; indistinct thin crossbedding; several thin purple shale beds at bottom of unit40.0

Total upper sandy member248.0

Medial silty member:

Covered; soil suggests earthy red siltstone; there may be small ledges of slickrim sandstone but none crop out; earthy siltstone, in beds less than 5 ft thick, probably is interbedded with subordinate thin shale; thickness computed from measured width and dip359.0

Lower sandy member:

Covered, probably sandstone, dark-pinkish-gray, very limy, very fine grained to medium-grained15.5

Purple clay parting1.0

Covered, probably reddish-brown earthy siltstone and fine-grained sandstone18.5

Sandstone, pinkish-gray, very fine-grained to medium-grained, thin, even beds, some sets of medium-scale crossbeds, poorly exposed25.0

Siltstone, reddish-brown, poorly exposed8.0

Sandstone, very limy, dark-pinkish-gray; weathers same; very fine grained to medium grained; moderately sorted; permeable; contains pink, black, and white quartz grains; very thin to thin even beds; 83 ft above base, 6-in.-thick purple siltstone with 6 in. of white siltstone on either side109.0

Covered, probably reddish-brown, earthy siltstone4.0

Covered, probably red shale6.0

Covered, probably reddish-brown earthy siltstone5.5

Shale, moderate-red with light-greenish-gray mottling, thinly laminated5.0

Siltstone, reddish-brown; composed of earthy siltstone and fine-grained sandstone 14.0

Sandstone, pinkish-white, well-sorted, fine-grained, bedding in distinct23.0

Covered; soil suggests reddish-brown earthy siltstone and fine-grained sandstone11.0

Sandstone, pinkish-white, very fine grained, well-sorted; contains some pinkish quartz and some black grains; no "Entrada berries" (coarse well-rounded quartz grains) noted; medium-scale crossbedding; forms soft rounded slickrim; concealed in many places; small covered zone in center probably is reddish-brown siltstone15.5

Total lower sandy member261.0


Total Entrada Sandstone868.0
NOTE.—The Carmel-Entrada contact is placed between the highest gypsum and lowest slickrim sandstone.
Carmel Formation:

Gypsiferous unit:

Siltstone, reddish and green, some gypsum seams59.0

Gypsum, white3.0

Siltstone, reddish, some gypsum beds and seams11.0

Siltstone, greenish, some red, some gypsum beds and seams30.0

Covered, mostly siltstone, reddish and greenish with red predominating, some gypsum seams and thin beds; some gypsum beds seem persistent but others are lenticular42.0

Gypsum, white2.5

Siltstone, reddish-brown2.5

Siltstone, light-greenish-gray, laminated, moderately cemented 4.5

Siltstone and gypsum; siltstone is moderate reddish brown and contains gypsum seams; gypsum in beds 1-4 ft thick forms one-third of unit34.0

Siltstone, mostly concealed, light-greenish-gray, laminated, moderately cemented23.0

Siltstone, very limy, orange-pink, small-scale crossbeds, abundant ripple marks; forms dip slope; thickness estimated4.0

Total gypsiferous unit215.5

Limestone unit:

Limestone, orange-pink, slightly silty; becomes siltier upwards3.0

Limestone, yellowish-gray, dense, thin beds, ripple marked 1.0

Conglomerate or breccia; more than half is matrix of siltstone that is reddish brown, limy, massive, contorted in places. Fragments range from pebbles to pieces more than 8 ft long, some angular, some rounded; most are limestone from underlying unit, but some large blocks are even-bedded siltstone and fine-grained sandstones; poorly exposed; probably formed by slump on depositional surface19.5

Limestone, yellowish-gray, dense, very pure, thin beds, ripple-marked6.0

Limestone, orange-pink, slightly silty; occurs as irregular flat very thin beds, a few thin interbeds of yellowish-gray limestone, and a few thin beds of limestone mud-chip conglomerate5.0

Interbedded siltstone (two-thirds) and limestone (one-third); siltstone is reddish brown, thin to thick bedded; limestone is orange pink, slightly silty10.0

Limestone, orange-pink, slightly silty, clayey.5

Siltstone, reddish-brown, clayey, very limy; thin to thick irregularly flat bedded5.0

Siltstone, reddish-brown, poorly sorted, slumped.5

Siltstone, moderate-reddish-brown; contains some clay and very fine sand; very thin to thin even beds with some interlaminae of shale of same color; ripple marks; some beds limy7.0

Siltstone, moderate-reddish-brown, poorly sorted with some clay and very fine sand; in slumped contorted units with fairly flat upper and lower surfaces14.0

Sandstone, dark-grayish-orange, medium-grained4.0

Sandstone, light-grayish-orange; weathers white; fine to very fine grained; thin to thick flat beds; reworked Navajo Sandstone16.0

Sandstone, dark-grayish-orange, medium-grained, abundant medium to coarse gray frosted quartz grains; bedding indistinct; part is low-angle, small-scale crossbedded, and part is irregularly flat bedded; weathers to form conspicuous grayish-brown ledge6.0

Total limestone unit97.5

Total Carmel Formation313.0
Navajo Sandstone (incomplete):

Sandstone, light-grayish-orange, somewhat paler toward base, fine-grained, moderately sorted, porous43.0


SECTION 17.—San Rafael Group
[At Red Slide, Hall Creek, sec. 9, T. 36 S., R. 9 E. (unsurveyed); lat 37°42' long 110°56'30". Measured by J. C. Wright and D. D. Dickey]

Thickness
(ft)
Morrison Formation (incomplete):

Salt Wash Sandstone Member (incomplete):

Top of measured section, not top of exposure.

Chert and calcite, white; weathers to show colored clastic(?) chert granules; some pyrite1.5
Summerville Formation:

Shale and siltstone, moderate-red, 1-in. to 1-ft thick interbeds of pale-red siltstone18.0

Shale, greenish-gray and dark-grayish-red, a few greenish-white silty fine-grained sandstone beds12.0

Shale (65 percent), moderate-red, interbedded greenish-white silty fine-grained sandstone (35 percent) in beds 3-9 in. thick11.0

Sandstone, silty, greenish-white, very fine grained; contains some gray frosted rounded medium grains ("Entrada berries"); thin to very thin even beds6.0

Shale, with minor siltstone beds less than 1 in. thick; much of shale is silty17.0

Shale, moderate-red, subordinate light-greenish-gray shale; about one-fourth light-greenish-gray siltstone in beds 6-12 in. thick11.0

Shale, moderate-red; about one-fourth pale-red siltstone in beds 1-12 in. thick16.5

Total Summerville Formation91.5
NOTE.—The Summerville-Entrada contact is mostly concealed; it appears conformable from a distance.
Entrada Sandstone:

Upper sandy member:

Sandstone, reddish-orange; weathers same; very fine grained, well sorted; "Entrada berries" conspicuous about 20 ft above base and also about 15 ft below top, sparse elsewhere; forms rounded slickrim-type cliff. Bedding as follows:

Feet above base
Top. Irregular flat thin beds171.0-177.0
Small- to medium-scale cross-strata142.5-171.0
Irregular flat thin beds141.0-142.5
Small- to medium-scale cross-strata138.0-141.0
Irregular flat thin beds134.0-138.0
Medium- to large-scale cross-strata95.5-134.0
Irregular flat thin beds92.5-95.5
Large-scale cross-strata in sets as much as 15 ft thick68.5-92.5
Irregular flat thin beds66.0-68.5
Similar to unit at base30.0-66.0
Irregular flat thin beds26.5-30.0
Base. Large-scale cross-strata in sets 3-6 ft thick.0-26.5

Total thickness177.0

Sandstone, silty, light-reddish-brown, very small scale to medium-scale cross-strata12.0

Total upper sandy member189.0

Medial silty member:

Covered by valley alluvium; presumably soft earthly siltstone with subordinate interbeds of slickrim sandstone; thickness computed from outcrop width337.0

Lower sandy member:

Sandstone, brown, very fine grained, some silt, moderately sorted; composed of rounded quartz grains, some of which are frosted; indistinct bedding, mostly irregular flat beds; a few medium-scale crossbeds in sets about 3 ft thick; weathers to rounded slickrim; middle part appears coarser and more distinctly crossbedded than the rest. Approximate thickness (precise dip determination impossible)332.0

Covered except for a few small exposures of red siltstone, dusky-red clayey material in the upper few feet, and several massive beds, probably contorted; forms recess19.5

Sandstone, white, fine-grained, well-sorted; composed of rounded quartz and a few reddish chert grains; well-cemented; probably medium-to large-scale planar sets of cross-strata, much jointed; forms ridge12.0

Total lower sandy member363.5

Total Entrada Sandstone889.5
Carmel Formation:

Gypsiferous unit:

Shale and shaly siltstone, soft-weathering, mostly concealed, pale-red, pale-purple, and yellowish-gray74.0

Limestone unit:

Covered, probably reddish-brown siltstone47.0

Shale, very limy, light-brown, some white bleached spots; weathers same8.0

Shale, silty, and reddish-orange siltstone, partly concealed11.0

Mostly covered; probably moderate-reddish-brown siltstone and minor sandstone7.0

Siltstone, sandy, white, moderately sorted, very calcareous, well-cemented; massive with casts of channels at base; forms ledge 2.0

Covered, probably reddish-brown siltstone as indicated by abundant float10.0

Sandstone, moderate-reddish-orange; weathers moderate brown; very fine grained; silty; well-cemented, calcareous2.0

Breccia; siltstone matrix (85 percent) with angular silty limestone fragments a fraction of inch to 6 in. across; probably formed by slumping12.0

Siltstone, moderate-reddish-brown, partly thin-bedded, partly massive; includes a few beds of massive very fine grained sandstone, same color16.0

Covered, probably similar to overlying unit3.0

Sandstone, pale-reddish-brown, very fine grained, massive beds 0.5-2 ft thick, separated by siltstone partings; uppermost bed is limy and capped by 2 in. of very limy ripple-marked sandstone8.0

Sandstone, moderate-orange-pink, fine- to medium-grained well-sorted; composed of rounded quartz grains; thin even beds; very thin bedded at top; appears to be reworked Navajo Sandstone8.0

Total limestone unit134.0

     Total Carmel Formation208.0
NOTE.—The Navajo-Carmel contact truncates cross bedding in the Navajo and is overlain by reworked sand from the Navajo.
Navajo Sandstone:

Sandstone, white, medium-grained, large-scale trough and planar sets of crossbeds300.0


SECTION 18.—The Morrison Formation in Long Canyon
[Lat 37°40', long 110°53'. Measured by G. A. Miller and B. L. Long]

Thickness
(ft)
Dakota Sandstone (incomplete):

Conglomerate, light-brown, crossbedded; contains light brown, white, gray, and sparse black rounded chert pebbles (average diameter 3/4 in., maximum 1-1/2 in.) in matrix of coarse-grained cherty sandstone 15.0
Morrison Formation:

Brushy Basin Shale Member:

Mudstone, light-olive-green to gray, bentonitic; largely covered by landslide blocks of Dakota Sandstone50.0

Mudstone, light-olive-green to light-gray, very bentonitic, massive, slightly sandy; weathers to light gray "popcorn" surface82.0

Mudstone and sandstone. Mudstone is olive green, bentonitic, and very sandy; it weathers to a "popcorn surface." Sandstone is light olive brown to light gray and very fine grained; it contains sparse grains of red and green chert9.0

Conglomerate, greenish-gray, crossbedded, lenticular; 1/4 in. red and green chert pebbles in very coarse grained mudstone matrix containing red and green chert and sparse clear quartz grains; a few partings of green mudstone2.0

Mudstone, bentonitic, light-olive-green to gray, massive; weathers to light gray "popcorn" surface3.5

Sandstone, mudstone and conglomerate, light-olive-green; sandstone is very fine grained to fine grained and contains sparse grains of red chert; mudstone is light green; conglomerate is olive green, lenticular, and contains abundant silicified wood fragments and pebbles of green mudstone unit poorly exposed8.0

Mudstone, light-purple to light-olive-green; contains sparse 2-in. beds of very fine grained to medium-grained poorly sorted light-gray sandstone6.0

Sandstone and conglomerate, light-gray; weathers dark brown; sandstone poorly sorted, fine to coarse grained, and very well cemented; conglomerate is mainly red and green chert pebbles averaging 1/4 in. in diameter. Unit is bench and ledge forming 2.5

Conglomerate, greenish-gray, well-cemented; contains 3/8-in. red and green chert pebbles in matrix of very coarse sandstone and sparse interstitial green clay1.0

Mudstone, light-gray-yellow grading downward to light-purple, bentonitic; contains well-cemented lenses of conglomerate containing 3/8—5/8-in. pebbles of red, green, and gray chert 33.0

Sandstone, light-gray; weathers to dark gray and dark brown; horizontally stratified; tightly cemented; well-sorted fine-grained sand with white interstitial kaolinite(?); locally cemented by carbonate3.0

Mudstone, light-purple to light-green, bentonitic, sparse 2-in. beds of gray very fine grained sandstone 14.5

Sandstone, light-gray to white, crossbedded, fine- to medium-grained, well-cemented at base, friable at top; upper 5 ft slightly conglomeratic; contains 1-in. white and gray chert pebbles. To north of this section unit contains abundant red and green chert pebbles14.0

Sandstone, light-gray, medium- to fine-grained, calcareous cement locally1.5


Total Brushy Basin Shale Member230.0

Salt Wash Sandstone Member:

Mudstone, dark-reddish-brown, slightly silty8.6

Sandstone, yellow-gray to light-brown, crossbedded, medium-grained, slightly conglomeratic; gray chert pebbles predominate over red and green chert43.2

Sandstone, very light brown to light-yellow-brown, very fine grained, horizontally stratified in 1-ft beds; some red mudstone at top of unit; tongues with red mudstone to west5.5

Sandstone, white to light-gray, trough crossbedded, medium- to coarse-grained; sparse conglomerate layers contain 1/2-in. pebbles of light-gray chert; lower 3 ft locally contains some red mudstone19.8

Mudstone, red-brown, silty; contains local 1-ft beds of light-brown very fine grained sandstone12.0

Sandstone, conglomeratic, light-brown to very light gray, cross bedded to horizontally stratified near top; sandstone very fine grained, limonite speckled; conglomerate contains pebbles of gray-white chert and sparse red chert and reddish quartz32.5

Sandstone, light-brown to brown, horizontally stratified in beds 1-2 ft thick, fine-grained to very fine grained, local layers of reddish mudstone6.0

Sandstone and conglomerate, light-gray to light-brown, medium- to fine-grained; few beds of reddish mudstone in basal 15 ft123.0

Mudstone, red; contains few thin beds of very fine grained silty reddish-brown sandstone6.5

Sandstone, light-brown to very light gray, horizontally stratified, fine-grained to very fine grained; few interbeds of dark-reddish mudstone11.5

Sandstone, very light gray, crossbedded, fine- to coarse-grained, locally conglomeratic, local beds of red mudstone as much as 6 in. thick34.0

Mudstone and sandstone; mudstone reddish; sandstone light gray to light olive green and very fine grained10.5

Sandstone, light-gray to white, crossbedded, very fine grained to coarse-grained, local conglomerate in beds as much as 2 ft thick8.0

Sandstone, light-gray to light-brown, in beds as much as 1 ft thick with interbeds of reddish mudstone16.0

Sandstone, conglomeratic, light-gray to white, medium- to fine-grained; conglomerate layers contain gray chert and quartz pebbles as much as 1/2 in. in diameter10.0

Sandstone, light-pinkish-brown, horizontally stratified in beds 1 in. to 1 ft thick, fine-grained; few 2-in. beds of green siltstone near top of unit4.0

Mudstone, reddish, silty and sandy, few local 3-in.-thick beds of very fine grained silty sandstone8.5

Sandstone, very light gray to white, crossbedded, medium-grained to very fine grained with abundant grains of pink chert; locally conglomeratic near base, with chert and quartz pebbles as much as 1/2 in. in diameter18.0

Sandstone, light-pinkish-brown, flat bedded in beds 3-5 ft thick15.8

Sandstone, light-pinkish-brown to light-gray; weathers tan and dark brown, horizontally stratified in beds 1-3 in. thick, fine grained to very fine grained4.6

Sandstone, light-gray to light-bluish-gray, horizontally stratified, very fine grained4.0

Mudstone, dusky-red, interbeds of red sandy and silty mudstone11.0

Limestone, light-blue; contains as much as 50 percent medium sized quartz grains3.0

Total Salt Wash Sandstone Member416.0

     Total Morrison Formation646.0
Summerville Formation:

Siltstone and sandstone, not measured in detail129.0


SECTION 19.—Morrison Formation on northwest side of Big Thomson Mesa
[Salt Wash Sandstone Member section begins at lat 37°43', long 110°56'; Brushy Basin Shale Member section begins 2,000 ft to the north. Measured by G. A. Miller and B. L. Long]

Thickness
(ft)
Dakota Sandstone (incomplete):

Conglomerate, gray; pebbles of gray and black chert in medium-grained sandstone matrix; well cemented; limonitic (not measured).

Mudstone, gray, shaly, carbonaceous5.0
Morrison Formation:

Brushy Basin Shale Member:

Mudstone, olive-green, poorly exposed, slightly sandy; contains a few 6-in.-thick beds of dark-green very fine grained well-cemented sandstone75.0

Mudstone, light-olive-brown, bentonitic, very sandy, poorly exposed; sparse interbeds of olive-brown very fine grained to fine-grained sandstone 4-6 in. thick18.0

Sandstone and conglomerate; sandstone is alternating olive green and light gray in bands 1-3 in. thick, crossbedded, fine to medium grained; conglomerate in lower part of unit is greenish gray, lenticular; contains pebbles of red and green chert, greenish-gray mudstone, and sparse gray chert15.0

Mudstone, light-olive-brown to light-olive-green, some red especially near base, silty, bentonitic, poorly exposed 91.0

Conglomerate, light-gray, crossbedded; average diameter of pebbles 1/2 in., maximum 2-1/2 in.; contains red and green chert, sparse red quartzite and gray chert, and some limestone fragments containing crinoids; matrix is coarse-grained to very coarse grained sandstone19.5

Mudstone, dark-red, silty, poorly exposed25.0

Sandstone, light-yellow-brown; weathers dark brown and dark gray; crossbedded; thick bedded; blocky; fine to very fine grained; calcareous cement2.5

Mudstone, red with some gray, silty, slightly bentonitic; few lenticles of massive-light-brown very fine grained calcareous cemented sandstone 7 ft below top22.5

Sandstone, light-gray; weathers dark brown; massive; very fine grained to medium grained; interstitial white clay (kaolinite?); calcareous cement1.5

Conglomerate; not present at location of Brushy Basin section, largely covered at location of Salt Wash section; variegated red, green, and gray, crossbedded, abundant pebbles of red, green, yellow, and minor gray chert in matrix of gray coarse-grained sandstone0-20


 Total Brushy Basin Shale Member270.0-290.0

Salt Wash Sandstone Member:

Covered; float and outcrops several hundred feet away are red mudstone10.0

Sandstone, pale-grayish-yellow to light-gray with small irregular patches of yellow, very fine grained, thick-bedded; contains sparse limonite specks and sparse granules and pebbles of chert12.0

Sandstone and conglomerate, very light gray, yellowish-gray, pale-orange, and light-greenish-gray; contains abundant limonite specks and stained areas; sandstone in beds as much as 3 ft thick is medium coarse grained to medium grained, cross bedded, and has conglomeratic layers along bedding planes; conglomerate, yellowish gray; consists of pink quartzite and chert, light-gray chert, and sparse clear quartz; average diameter of subrounded to rounded pebbles is 1/4 in., maximum 1 in. Upper 10 ft of unit is yellow gray to pale orange and is less conglomeratic than lower part31.5

Sandstone, silty, moderate-yellow-brown to dark-brown, very fine grained, horizontally stratified1.8

Sandstone and conglomerate; sandstone is dark yellowish orange to pale yellowish orange, medium fine grained, crossbedded in beds 1-3 ft thick; conglomerate interbeds are 3-5 ft thick, crossbedded, moderate yellow to pale yellowish-orange; pebbles average about 0.4 in. in diameter and are composed of yellow and gray chert and sparse red chert7.0

Conglomerate, brown to dark-gray, subangular to rounded pebbles of white, gray, and brown chert and sparse milky and rose quartz; average diameter of pebbles is about 3/4 in., maximum 2 in.15.0

Sandstone, light-brown to grayish-orange medium-grained; principally quartz and abundant grains of white altered chert(?); abundant limonite specks14.0

Conglomerate, light-gray; basal 1 ft contains sparse blocks of sandstone 3 in. thick and 12 in. long and pebbles of light-gray chert, green mudstone, clear quartz, and sparse red chert; abundant granule-sized grains; grades upward into overlying unit 3.0

Sandstone and conglomerate, light-gray to pale-orange-brown, fine- to coarse-grained, calcite cement, crossbedded; pebbles average about 0.4 in. in diameter, mostly dark-gray silicified limestone, quartzite, and gray chert; sparse red chert; sand grains and chert pebbles rounded to subrounded, other pebbles subangular30.0

Sandstone, pinkish- to yellowish-gray and very light gray; weathers white to light gray; very fine grained; well sorted; sparse granules and pebbles of dark-gray chert5.0

Covered (talus and landslide); sparse outcrops in this interval within a few hundred feet of section are red mudstone and thin lenticular sandstone similar to underlying unit143.5

Sandstone: lower 4 ft light gray, fine grained; upper 3 ft medium to coarse grained. Unit contains abundant grains of red chert, sparse granules of red and gray chert along some bedding planes; it is horizontally stratified and crossbedded, very lenticular, and appears to pinch out 20 ft north of section7.0

Sandstone, light-grayish-yellow, fine-grained to very fine grained, laminated; laminae about 0.1 in. thick, conspicuous on weathered surface5.5

Sandstone, light-reddish-brown to light-gray, medium- to medium-coarse-grained, crossbedded, abundant limonite specks; sparse pebbles of light-gray chert along bedding planes; forms cliff22.0

Mudstone, reddish, poorly exposed2.0

Conglomerate, light-gray to grayish-pink; average diameter of pebbles is about 1/2 in., maximum 2 in.; mostly white and red chert, some green chert, quartzite, sandstone, and clear quartz5.0

Sandstone, conglomeratic, light-gray to pale-reddish-brown; weathers dark reddish brown. Average diameter of pebbles is about 1/2 in., maximum 1-3/4 in.; consist of chert, clear quartz, dark-gray quartz, quartzite, and sparse sandstone and silicified limestone; limestone pebbles contain impressions of crinoid stems. Unit is crossbedded, has numerous scour and fill structures; cliff former28.0

Sandstone, very light gray, very fine grained; contains abundant black opaque minerals and green chert(?) grains; horizontally stratified; tightly cemented by calcium carbonate(?)4.0

Mudstone, silty, dark-red4.0

Sandstone, conglomeratic in lower 3 ft, light-gray, speckled with limonite, very fine grained to coarse-grained; pebbles angular to subangular, gray to grayish-red chert and sparse clear quartz, average about 1/2 in. in diameter; sparse coarse grains of white chert(?) in sandstone; unit forms cliff, fills scour in underlying unit32.5

Sandstone, very silty, reddish-brown to light-red; very fine grained, poorly exposed1.0

Sandstone, light-reddish-brown, very fine grained to fine-grained; contains sparse flakes of green claystone; abundant limonite; horizontally stratified in beds as much as 1.5 ft thick; weathers pale red5.5

Sandstone, white to very light gray, fine-grained with sparse pebbles of light-gray chert as much as 1/2 in. in diameter scattered along bedding planes; crossbedded; abundant limonite specks; sparse black opaque mineral grains; weathers pale yellowish brown; unit contains numerous scour structures; top of unit is horizontally stratified11.7

Sandstone, very silty, light-yellowish-brown, very fine grained; abundant limonite stains on outcrop; occurs in beds about 6 in. thick2.4

Sandstone, very light gray, very fine grained to fine-grained; sparse grains of red chert and flakes of olive-green mudstone locally; horizontally stratified in beds as much as 1.5 ft thick3.3

Sandstone and mudstone; alternating pale-green mudstone and light-pinkish-red, very fine grained, well-sorted sandstone in beds 1-4 in. thick3.0

Sandstone, silty, reddish-brown, very fine grained, tightly cemented, horizontally stratified3.0

Sandstone, slightly conglomeratic, light-gray, fine- to medium-grained; pebbles rounded to angular light-red quartz and gray chert as much as 1 in. in diameter; pebbles scattered along bedding planes throughout unit; sparse black opaque mineral grains and sparse grains of weathered chert(?). Unit is the stratigraphically lowest scouring sandstone in the Salt Wash in this area19.0

Sandstone, light-gray to pinkish-gray, very fine- to coarse-grained; horizontally stratified to crossbedded; crossbedded portions are poorly sorted3.8

Sandstone, very light gray, very fine grained; locally yellow brown due to limonite specks; horizontally stratified in beds 1-1.5 ft thick2.7

Sandstone, very silty, slightly calcareous, pale-reddish-brown, very fine grained to fine-grained, poorly sorted1.0

Sandstone, light-gray, very fine grained, horizontally stratified; weathers yellowish brown1.7

Sandstone, light-gray to olive-brown, very fine grained; contains abundant limonite specks, sparse black opaque minerals; laminated in beds about 0.6 in. thick; upper 2 in. of unit contains medium-grained sand and is poorly sorted; forms ledge2.4

Mudstone, silty, very dusky red to dark-reddish-brown; sparse beds of light-grayish-green mudstone near top; upper 3 ft contains lenses of light-yellowish-gray very fine grained sandstone that contains sparse flakes of carbonaceous material6.7

Sandstone, very tightly cemented with silica, yellowish-gray to light-olive-gray, very fine grained; weathers light olive gray; local blebs of green mudstone in lower 2 in.; forms conspicuous ledge 1.6

Mudstone, sandy, grayish-olive to grayish-green to pale-red along outcrop1.0

Sandstone, yellowish-gray to greenish-gray, very fine grained, crossbedded, small flakes of carbonaceous material locally, very lenticular, grades into greenish-gray mudstone in nearby outcrops 2.2

Mudstone, silty, reddish-brown; contains 6-in.-thick beds of light-yellowish-green siltstone locally; upper 1 foot contains sparse light-pinkish-red nodules of calcareous siltstone8.5

Sandstone, light-yellowish-gray, very fine grained, horizontally stratified, well-sorted; poorly exposed.8

Limestone, cherty, light-yellowish-gray to bluish-gray; sugary to medium-crystalline; chert is red, in irregular beds near top of unit; weathers light olive gray; taken as base of Salt Wash Sandstone Member of Morrison Formation2.5


Total Salt Wash Sandstone Member466.6

     Total Morrison Formation736.6-756.6
Summerville Formation:

Siltstone and sandstone, red, ribbed, thin-bedded (not measured).


SECTION 20—Dakota Sandstone at "The Post"
[East-central Circle Cliffs area, Garfield County; lat 37°50' long 110°58'20". Measured by G. A. Miller]

Thickness
(ft)
Mancos Shale:

Tununk Shale Member:

Mudstone, dark-gray, thinly laminated to very thin bedded, bentonitic, highly weathered, poorly exposed (not measured).
Dakota Sandstone:

Sandstone, light-brown to dark-gray, ripple-laminated, medium- to coarse-grained; contains granules of quartzite and tan chert; fossiliferous (Ostrea)2.5

Sandstone, light-yellow, horizontally stratified and crossbedded, fine- to medium-grained; very coarse grains and granules of gray chert and quartz in upper 3 ft7.0

Sandstone, brown to dark-gray, horizontally stratified in ledgy beds 1-2 in. thick, carbonaceous, fine-grained to very fine grained 1.5

Shale and coal1.5

Sandstone, gray, massive, carbonaceous, very poorly sorted fine- to coarse-grained1.0

Shale and coal2.5

Siltstone, gray; weathers to light gray; massive; sandy2.5

Shale, light-gray, very sandy, some ledges of fine-grained sandstone 3.0

Sandstone, brown to white, horizontally stratified to crossbedded, limonitic, fine-grained to very fine grained, beds near top are ripple laminated7.0

Shale, gray to light-olive-gray, sandy, few thin beds of fine-grained sandstone12.0

Sandstone, white to pale-yellow, red near top; weathers light brown; crossbedded; well sorted; fine to very fine grained26.0

Sandstone, largely covered, float similar to overlying unit 8.6

Conglomerate and sandstone, light-yellow to gray; conglomerate weathers dark gray to black, crossbedded; pebbles as much as 2 in. in diameter of dark-gray to black chert, gray chert, and sparse quartzite 11.0


Total Dakota Sandstone86.1
Morrison Formation (not measured).

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Last Updated: 04-Jan-2010