Geological Survey Bulletin 1673 Selected Caves and Lava Tube Systems in and near Lava Beds National Monument, California

Tickner and Berthas Cupboard Caves and Tickner Chimneys

Unlike most large lava-tube cave systems in Lava Beds National Monument, Tickner and Berthas Cupboard Caves (map 9, pl. 3), along with Valentine Cave (map 8, pl. 3), did not originate from molten lava erupted from Mammoth Crater. Instead the Tickner Cave lava reached the surface through vents associated with a northwest-trending fissure system on the north slope of the Medicine Lake volcano 1 mi southeast of Mammoth Crater (fig. 4). This lava flowed north then east to Valentine Cave and beyond. It overlies the basalt of Mammoth Crater and is known as the basalt of Valentine Cave (Donnelly-Nolan and Champion, 1987). Small agglutinate cones known locally as the Tickner Chimneys are the most conspicuous features of the vent area, but an interesting network of small lava tubes is present both on the surface and stacked at shallow depths along fissures. Many small spillover lobes of lava were formed during the final stages of eruptive activity.

The material that built this lava field was transported almost entirely through lava tubes; the main tubes preserved are Tickner and Berthas Cupboard Caves. J.D. Howard explored these features in the 1920's (his notes are on file at the Visitor Center). He named Tickner Cave and the Tickner Chimneys after H.C. Tickner, an early freighter who lived in Yreka and pioneered the Tickner Road (map 9, pl. 3), an important wagon route in the late 1800's.

Howard also found a cave at a lower level, which extends the cave system to the northeast, and named this deeper level Berthas Cupboard Cave in honor of Bertha Heppe, the wife of an early homesteader in the area. The word "cupboard" refers to the shelf-like openings and irregular small grottos that lie between flow units of lava in the southeast corner of the well-like breakdown forming the main entrance. They are shown in a schematic cross section on map 9, plate 3 and also in figure 37.

Figure 37. Entrance area shows stacked holes that lent name to Berthas Cupboard Cave (see fig. 4 and map 9, pl. 3).

Tickner Road, a little-traveled dirt road through the logged-over forest just south of the monument boundary, is the only access road to this area. Tickner Road crosses a collapsed and filled part of Tickner Cave (map 9, pl. 3) at a point about 1 mi (by road) east of the junction of Tickner Road with the Medicine Lake-Lava Beds Road. The caves are unmarked; the land survey location of this crossing is in the NE 1/4 sec. 5, T. 44 N., R. 4 E. An abandoned logging road joins Tickner Road 200 ft west of the Tickner Cave crossing and provides access to the Tickner Chimneys farther upstream to the south.

The position of Tickner and Berthas Cupboard Caves is easily located because of the line of collapse pits and trenches formed along roof cave-ins (fig. 38). This line is at the center of the lava flow, which trends north and then northeast. The surface of the ground slopes away on either side. Near the downstream end of the lava field, Berthas Cupboard Cave is so filled with ponded lava and collapse debris that it can no longer be traversed. The underground tube, however, must have continued northeast because small patches of aa broke through and welled out of cave roofs at points along the eastern continuation of this line.

Figure 38. Surface collapse of upper tube allows entrance to Tickner Cave (see fig. 4 and map 9, pl. 3). Gentle arch shape over tube is a common feature of tube-bearing basalt flows.

Farther upstream, during early and late stages of volcanism, lobes of pahoehoe flowed from skylights and fissures in the roofs of the Tickner and Berthas Cupboard tubes. These spillover lobes were important components in building the apical ridge along the sloping surface of the lava flow.

Tickner Cave

The upper entrance to Tickner Cave is at the northeast end of a lava chute 10 ft wide that increases from 2 to 10 ft in depth downstream. This chute marks the site of a 150-ft-long former cascade in a surface stream of molten lava that flowed downhill on a 10° slope. Horizontal striations preserved on the walls of the chute indicate places where viscous lava was dragged against the walls. The gradient became shallower at the northeast end of the chute where the lava plunged underground into what is now Tickner Cave. Spatter on the rims of the chute and over the roof of the cave entrance testifies that limited fountaining of the molten lava took place at the point where it surged underground.

From this point Tickner Cave can be traversed for 1,450 ft downstream. At several places along its course molten lava broke out onto the surface through skylights and medial cracks along the axis of the roof. Along the lowest 500 ft of its course, lava in the tube leaked down through at least three holes in its floor into the upstream part of underlying Berthas Cupboard Cave.

Throughout its extent Tickner Cave lies very close to the surface. Many collapse holes (fig. 39) reveal a roof thickness of only 1-4 ft. In places along the axis of the cave slabs of roof rock were raised and tilted. In some of these arched areas evidence indicates that parts of the broken roof collapsed during volcanism. The lava flowed in up to 100-ft-long gutter-like open streams along the axis of the tube. Contact with the air caused solidification on the sides and surface of the molten stream. Thus most of these gaps were soon bridged over with a solid lava cap that was gradually thickened from below and welded onto broken edges of the former roof. As a result, the ceiling height of Tickner Cave varies considerably. The ceiling today contains many cupolas and domes, which were either former skylights or collapsed parts of the former roof now joined to the collapsed walls by coatings of several layers of lavacicles and dripstone. Only where parts of the roof have subsequently collapsed can one see the separate coatings of lava plaster and the successive linings of lavacicles and dripstone. These layers reveal that Tickner tube was repeatedly filled and drained of molten lava and that much lava spilled onto the surface.

Figure 39. Pair of collapse holes along Tickner tube forms this natural bridge near entrance to Tickner Cave (see fig. 4 and map 9, pl. 3).

The floor of Tickner Cave is also complicated by many interesting features caused during the partial draining of the last lava to occupy the tube. Because remnants of this final flow form numerous balconies clinging to the walls of the cave, we named it the "Balcony flow."

During the downstream flow of the molten lava, a roof collapse occurred 200 ft upstream from the lower end of Tickner Cave at the broad part of the paddle-shaped collapse trench. The lava backed up behind this barricade and filled half the tube as far as the upstream entrance of the cave. The lava lifted the cave's roof on the west side of the collapse and poured out on the surface, tilting part of the roof to a right-angle position as it opened an exit (map 9, pl. 3). Another part of the lava, however, flowed around the sides of the collapse pile forming the two small tubes on either side of this paddle-shaped feature. Also, an irregular plexus of tiny lava lobes burrowed beneath the collapse debris; some drained out and left open lava tubes large enough to crawl into. Furthermore, at least three main areas of leakage occurred through the floor of Tickner Cave; lava dumped into the upstream part of Berthas Cupboard Cave below. One of these leaks is 100 ft upstream from the paddle-shaped collapse (map 9, pl. 3). Two others are still farther upstream at the head of two branches in Berthas Cupboard Cave; the branch on the east forms the now rubble-filled upper Crawl entrance to Berthas Cupboard, the one on the west is completely blocked with collapse debris.

During the waning stages of volcanism, a surface of lava developed within Tickner Cave that fluctuated only a foot or two in height because incoming lava was essentially in equilibrium with the amount of lava both detouring around the paddle-shaped barricade and leaking into Berthas Cupboard Cave. This equilibrium allowed a crust of solidified lava to form on top of the flow, and so a "false floor" was built completely across the tube upstream from the area of collapse. This crust, however, was unstable; slight fluctuations in the amount of lava heaved it up or let it sag from lack of support. Moreover, the crust was thin over the wider and deeper parts of the lava tube, where large pools of molten lava retained elevated temperatures for a longer time. The crust was stronger and thicker in the narrow, quicker cooling parts of the tube. Finally, with cessation of volcanism, much of the molten lava beneath the crust drained into Berthas Cupboard Cave. This drainage resulted in large sections of the thin crust in the wider parts of the cave collapsing and being carried away. However, along the walls, where the crust was thicker and more rigid, extensive remnants were left clinging to the walls as benches (fig. 40). In narrower parts of the tube the crust remained essentially intact as an underground natural bridge, with a tube-in-tube forming a culvert beneath it.

Figure 40. Pronounced benches form lower walls of Tickner Cave (see fig. 4 and map 9, pl. 3) near entrance. Benches formed when molten interior of lava flow half-filling the tube flowed away and left chilled rind against walls.

The difference in shape of Tickner Cave compared to most other lava tubes is immediately apparent upon entering this cave. The floor, instead of rising gradually into the dripstone walls, intersects the walls at an acute angle. At the junction is a bench with an irregular top 1-3 ft high and seldom more than 3 ft wide. It is made up of thin slabs of congealed lava, some of which tilt up steeply from the junction of floor and wall and have irregular broken edges. Other slabs extend out nearly flat and then sag down from the walls, whereas still others turn down and curl in toward the wall. These thin slabs of broken or curled lava record minor fluctuations in the height of the molten lava surface within the tube. Such fluctuations allowed thin, fragile crusts of rock called peeled linings to congeal and extend outward from the walls for a foot or more before they were either broken and heaved up by a slight rise in the level, or were let down and curled under as the height of the lava flood subsided a few inches. Low benches of these broken and curled lava crusts are nearly continuous on both walls in this part of the cave.

Notice, also, that the cave does not have the typical oval cross section of a completely drained lava tube; instead it appears to be the upper part of a much larger lava tube that is now half- to three-fourths filled with congealed lava. We will find this inference of a partly filled larger tube to be true as we traverse downstream. This upper part of the Tickner tube is illustrated and explained in the cross section near the upper end of map 9, plate 3.

Downstream 180 ft from the upper entrance, and just beyond a low area in the roof, the floor of Tickner Cave changes markedly. The well-developed pahoehoe ropes are less prominent in some areas and completely absent over large areas. The surface is smooth, similar to that developed where lava has ponded, but this floor is not like the smooth level surface of the lava ponds in Valentine Cave. Instead the floor sagged irregularly into small basins separated by hummocks. Many hummocks with short cracks on their crest are shaped like miniature schollendomes. Moreover, the broken and curled slabs that formed benches along the walls are either lower or absent in this area, but in places the smooth pahoehoe shows evidence of having been stretched and dragged downstream against the walls. Finally, at a point 300 ft downstream from the entrance, or 100 ft upstream from where Tickner Road crosses Tickner Cave, the smooth floor breaks up into slabs 2-10 ft across (fig. 41). These slabs were rafted forward and jostled together, a process that produced a floor jam as much as 6 ft high and 25 ft long, which extends across the cave. The downstream edge of this floor jam is an amphitheater-like scarp. Below it a frozen lava cascade, containing rafted blocks from the floor jam, descends to the true floor of the lava tube 12 ft below the level of the balcony floor at the top of the floor jam. Evidently this frozen cascade marks the place where the final part of the Balcony flow kept moving below its solidified crust during the waning stages of volcanism. The moving lava carried away large parts of its former crusts, below the lip of the amphitheater, and the remaining crust sagged into a hummocky and partly floor jammed surface for another 150 ft downstream.

Figure 41. Buckled floor plates of Tickner Cave (see fig. 4 and map 9, pl. 3) formed when interior of lava flow drained away, and chilled pahoehoe surface lost support.

For a short distance below the collapse amphitheater, passage is blocked by the fill for Tickner Road and by collapse breccia. Access to the surface is provided by a crawlhole that emerges on the south edge of the road (South Road entrance) and reentry to the cave by both a small crawlhole (North Road entrance) and a large oval roof collapse 250 ft north. There are also three holes through the roof of the tube between Tickner Road and this large oval collapse (see map 9, pl. 3).

The most striking features in Tickner Cave between the road and the oval collapse are large remnants of the Balcony flow, which hang as true balconies above the present floor of the cave. These balconies have turned-down edges and curl back into an overhang in places. Of particular interest are remnants of the flow (one oval, the other pear-shaped), which are not attached to the cave walls, standing isolated within the drained area (map 9, pl. 3). The oval remnant has a top that is tilted up on its edges like a saucer; the pear-shaped one is tilted downstream, but the direction and amount of tilt are not the same as that of the nearby wall-attached balconies. The most logical explanation is that these two remnants broke loose from the east wall, as the lava flood withdrew from beneath them, and then slid toward the central part of the cave. The surface of these isolated remnants is lower than that of adjacent wall-clinging balconies, a fact which supports the inference that they slid downhill from their former positions. The floor of the cave in this area is a jumble of slabs of collapsed balcony (map 9, pl. 3).

One of the most instructive areas of balcony collapse is a 100-ft stretch of Tickner Cave between the northeast edge of a large oval roof collapse and the point downstream where it narrows abruptly near the north side of a pillar in its west wall. In the wide cavern upstream from this narrow spot a remnant of the Balcony flow 80 ft long and 5 ft wide hangs from the east wall 8-12 ft above the floor of the cave. On the opposite (west) wall of the tube the remnant counterpart is only 1-2 ft wide and is missing from the southern part of the cave wall. On the floor of the cave, however, rests a huge block from this balcony. It is 45 ft long and tapers in width from 14 ft at its south end to 2 ft at its north end. This balcony remnant toppled out from the west wall and now lies on its side, with its pooled pahoehoe surface vertical and facing east. Molten lava was evidently flowing through the tube when the block broke away from the west wall and toppled eastward, because the upturned face of the block shows spatters of lava and pieces of fallen lavacicles upon it. The relatively smooth broken-off wall of the cave west of this block contains small ridges and troughs running horizontally that can be matched exactly with corresponding features on the upward-facing surface on the fallen block.

The broken-off west wall contrasts noticeably with the east wall—the east wall is embellished by one of the most spectacular and photogenic displays of dripstone in any cave described herein. The last thin coating of brown dripstone that ran down this wall probably came from the liquid lava splashed against it when the block from the west balcony toppled.

The pillar at the downstream end of this room has a small tube routed through its west side. The floor of this small tube hangs a few feet above the surface of the balcony. Downstream 50 ft farther, the intact balcony becomes the actual floor of the cave and forms a wide natural bridge within the cave. Beneath this bridge, molten lava was conveyed downstream through a tube-in-tube. This culvert-like drain is now only 2-5 ft in diameter because successive linings of lava plaster almost closed off the space between its walls, roof, and floor. Only the downstream one-fourth of this tube-in-tube is large enough to crawl into. The broken-off upper end of the tube reveals the linings that successively diminished the size of the tube-in-tube. The thin edge of the large toppled block of balcony described previously is jammed against the east wall, alongside the upstream end of this culvert.

At its downstream end the tube-in-tube emerges onto a lava floor at the west edge of another amphitheater-like lava cascade, similar to but not as high as the one above Tickner Road. This new floor, 4-7 ft lower than the balcony level, disappears another 40 ft downstream beneath the rubble of a 200-ft-long roof collapse. Apparently, the lava in equilibrium with this lower-floor level was draining into Berthas Cupboard Cave through the two cataracts exposed at the head of that cave. A low crawlway (the Crawl entrance) through the collapse rubble is formed by the southeastern cataract; the northwestern crawl is completely blocked by massive collapse debris.

Downstream from the next 200-ft-long roof collapse, the floor of the cave is also a part of the Balcony flow. Here, however, it formed a smooth pool of lava ponded against the barricade formed by the floor jam at the head of the paddle-shaped collapse farther downstream in the Club Room. As noted previously, molten lava escaped from beneath this pooled surface via the two small tubes on either side of the barricade. At the downstream end of the 200-ft-long collapse, the lava also escaped by a tube plunging through the east wall that fed into Berthas Cupboard Cave 200 ft farther downstream from the cascades at the head of Berthas Cupboard Cave.

Tickner Cave loses its identity as a large lava tube at the head of the paddle-shaped collapse (map 9, pl. 3). Here, as noted earlier, part of the molten lava rose and spilled out at the surface, in separate lobes, while more flowed underground around and below the collapse debris. Much of the molten lava, however, had already exited the tube through the two cataracts, which enter Berthas Cupboard Cave 300 ft upstream from the Club Room at the head of the paddle. By the time the Balcony flow had crusted over, perhaps all of the lava flowing through Tickner Cave was draining into Berthas Cupboard through these cataracts.

Small tubes and other fascinating features are present in and around the paddle-shaped collapse at the Club Room. The collapse debris at the broad head of the paddle has been smoothed and rounded, like a ship's prow, by the lava that advanced around its sides. Blocks in this area were cemented into a tight mass by lava that flowed along the former cave floor. Part of the collapse debris was overrun by tongues of molten lava that broke through to the surface and, in the process, turned parts of the cave roof on end, and then they spilled northwest as a surface lobe. Details of the edges of this surface lobe, however, are obscured by later accumulations of pumice and windblown sand. Downstream from the paddle a small underground tube continues to the northeast; part of it has collapsed to form the handle of the paddle, but a section of a tube-in-tube within it remains intact. The remaining roofed-over section of the tube continues northeast for 25 ft beyond the end of the paddle's handle. Beyond the handle it is filled to the roof with a spiny pahoehoe formed by lava so viscous that it congealed into large ropes transitional to aa lava. This tube is barely beneath the surface of the ground. Its 3-ft-thick roof arches above the ground surface, and a medial crack runs through the roof along the entire course of the tube.

Berthas Cupboard Cave

Because the upstream part of Berthas Cupboard Cave (map 9, pl. 3) is at a deeper level than Tickner Cave, and also received leaking lava from Tickner, Berthas Cupboard must have formed independently from a flow of lava underlying the Tickner flow. At its downstream end, however, Berthas Cupboard Cave filled with lava transmitted to it through the Tickner lava tube. Still farther downstream this lava burst through to the surface and formed small aa flows. Therefore the lava tubes are all parts of one large system having its origin in the fissures beneath the Tickner chimneys and vents farther south. The tubes were the principal conduits through which this molten lava was transmitted north and northeast to build the basalt of Valentine Cave.

The upper part of Berthas Cupboard Cave is divided into two parallel tubes that are interconnected with one another around the ends of one small and three large pillars. Both tubes are floored by gently sloping lava flows, which rise southwest along the sides of the pillar farthest upstream; both are demolished upstream at the head of this pillar by a roof collapse.

The tube on the southeast side of the pillar contains rough balconies that rise above the central cascade on both wall and pillar sides. These balconies are remnants from the collapse of a tube-in-tube. Upstream the roof collapse hides both cascade and balconies, but a crawl hole through the collapse blocks provides the small upstream entrance to Berthas Cupboard Cave from Tickner Cave, as indicated on map 9, plate 3.

The parallel tube on the northwest side of the pillar is similar but even more complex. It contains remnants of more than one tube-in-tube. Some remnants form balconies along the sides of the tube, and other partly collapsed segments of tube-in-tubes clutter areas along the center of the larger tube. Upstream this complex tube subdivides into two tubes, one of which is at a higher level and slightly offset from the lower one. Farther upstream the whole network of tubes is buried beneath the collapse rubble at the head of the pillar. Some complications among the tube-in-tubes in both branches around this pillar surely were caused by recurrent violent cascades of lava, which leaked from overlying Tickner tube into both branches of Berthas Cupboard Cave.

At the downstream side of this pillar the two branches of Berthas Cupboard Cave unite in the Mush Room, a room 50 ft wide and 60 ft long, floored by pahoehoe, which spread out and pooled at the foot of the cascades that debouched from both branches. From the center of this pahoehoe pool rises another pillar—the Mushroom—only 6 ft in diameter at floor level, which widens into a 27-ft oval-shaped slab where it joins the roof (fig. 42). Evidently the lower parts of the pillar were spalled and rafted away by the lava flowing around it. The remnant at the roofline continues the trend and medial position of the group of three long pillars shown on the map.

Figure 42. Large pillar in Berthas Cupboard Cave (see fig. 4) is known as the Mushroom (see map 9, pl. 3).

From the Mush Room, the lava tube subdivides around the next long pillar downstream. The main flow was along the northwest side of the pillar. A roof collapse chokes much of the smaller southeast tube and leaves only a crawlway at its upper end. Evidence of tube-in-tubes such as those upstream is not present here, but almost continuous small benches, 1-3 ft high, and seldom wider, project from both walls and encircle the two large downstream pillars. These benches are made of many sheets only 1-3 in. thick that solidified as crusts from the walls of the molten lava and curled down (fig. 43) or broke off as the lava changed in level. They have the same origin but even better form than the benches at the upper end of Tickner Cave.

Figure 43. Curled lining of Berthas Cupboard Cave (see fig. 4 and map 9, pl. 3) peeled away while still hot.

The last of the large pillars downstream is canted at a slight angle to the west wall. The tube on the northwest side of it therefore narrows downstream where a large floor jam piled up. It consists not only of slabs from the floor, but also of rafted blocks from the collapsed tube-in-tubes upstream and some debris from roof collapses. Downstream from this last pillar the combined flow narrows into one tube, which narrows abruptly to 15-20 ft another 75 ft farther, only one-third of its upstream width. In this narrow section the benches of curled-lava plates change to higher and broader balconies, with turned down edges covered with dripstone. This tube decreases to a width of only 12 ft with a height of less than 5 ft. A very low tube-in-tube occupies the center of the passage for nearly 70 ft; on either side the floor consists of plates buckled by the last lava flow into waves 1 ft high and 6 ft crest to crest. A lava boil 1 ft high and 12 ft wide nearly closes off this passage at the Gates of Dis. Beyond the Gates of Dis, the tube suddenly broadens downstream into a high-domed chamber 75 ft long, 40 ft wide, and originally 27 ft high at the apex of the dome. This room has shelf-like openings in its walls and at several levels of the arched sides of the dome. These are separations between flow units that have been pulled apart. Grotto-like clefts also break across flow units and extend outward into the walls. Two collapses to the surface are closely associated with this dome: one is a small cupola (11 ft in diameter) that demolished part of the sloping roof of the northwest part of the dome and left a shelf of debris against the northwest wall, and the other is a large irregular collapse pit roughly 40 by 30 ft at the surface with a floor that is at the same level as the floor of the dome. This larger collapse, which provides the main entrance to Berthas Cupboard Cave, lies only a few feet downstream from the edge of the dome, but the connection between them has such a low ceiling that one must stoop to enter the dome. Also like the dome, this collapse pit contains several open separations between the flow units exposed on its walls. It is these shelf-like openings on the walls of this pit, and the irregular grottos between them, that prompted Howard to name the cave Berthas Cupboard (see fig. 37 and the sketch of this breakdown on map 9, pl. 3.)

Within the dome, collapse fragments dropping from these shelf-like separations have built a ring of debris on the floor of the cave near its walls. An arcuate ring of tumbled debris, 5-15 ft high, borders the west rim of the dome. Many pieces dropped from the sloping roof of the dome and from edges of flow units in the dome's walls when the rock was hot and plastic. They welded together on impact. This arcuate ridge of collapse debris is also responsible for the low ceilings that must be negotiated when leaving the dome in either direction. A short natural bridge is present at the southwest corner of this debris ring.

Downstream from the dome, Berthas Cupboard Cave can be traversed for 650 ft before access is denied by partial lava filling and roof collapse. This part of the cave has a thick covering of collapse debris compared with the upstream part of Tickner Cave. It is a typical near-surface lava tube ranging from 20 to 30 ft wide. It is also wetter than the upper parts of the cave. The latest lava flow formed a gently sloping floor of pahoehoe with the lava fill gradually increasing downstream. Pahoehoe ropes also tend to be more spiny and broken farther down the tube. Approximately 160 ft downstream from the entrance pit a section of jammed floor blocks marks the start of a section of intact roof called The Silver Lining after the reflections from water droplets on its surface. Debris from roof falls is scattered along the floor and rises in several large collapse mounds. A particularly large pile of roof-collapse debris almost closes the tube in the area where the tube changes direction from northeast to east. Entrance to the final 250 ft of the cave requires negotiating a very tight, wet crawlway. In this final segment a tube-in-tube exposed in the cave roof above another floor jam of blocks can be explored for 35 ft. Farther downstream a small side tube surrounds a pillar on the north wall of the cave; a few feet beyond this pillar access is denied by a roof collapse. Although the collapse prevents a crawl to the surface, it is apparent that the surface is not far above because warm air can be felt descending into the cave and small animals make their homes here.

Tickner Chimneys

The Tickner Chimneys (map 9 inset, pl. 3) were not studied in detail. Most of them surmount the fissures through which the basalt of Valentine Cave was erupted. Additional spatter vents lie farther south along the same trend and are not shown on the map. The chimneys are small agglutinate cones, most of which are less than 5 ft high. They formed where clots of molten lava fountained and accumulated along the fissure. A few chimneys rise from smaller fissures parallel to the main one. Some chimneys are connected underground by short lava tubes, which trend along the course of the fissure. Surface features in the vent area also include many lava gutters and spillover lava lobes. Many of the small agglutinate cones have miniature spillout lava lobes and tiny surface lava tubes radiating from them. Unfortunately a thick coating of pumice and an almost impenetrable thicket of mountain mahogany prevents close inspection of many of these small-scale features. Therefore we prepared only a reconnaissance map of the vent area, at a different scale from the map of the caves. The visitor interested in acquiring a knowledge of this kind of vent area is better advised to visit the excellently exposed Ross Chimneys (fig. 44) in the monument.

Figure 44. Ross Chimneys in north-central Lava Beds National Monument are similar to poorly exposed Tickner Chimneys, outside monument. Spatter vents formed by accumulation of hot lava spatter blown into air from an erupting fissure. Hammer on middle chimney for scale.