Geological Survey Professional Paper 754—B The Copper Harbor Conglomerate (Middle Keweenawan) on Isle Royale, Michigan, and its Regional Implications

Cover

Abstract

Introduction

Scope of study
Acknowledgments

Copper Harbor Conglomerate on the Keweenaw Peninsula of Michigan

Copper Harbor Conglomerate on Isle Royale

Location and areal extent
Thickness
Lithologic character
     Texture
     Composition
Distribution of rock types
Direction of sedimentary transport
     Sedimentary structures as directional indicators
     Lateral changes in texture and formational thickness as directional indicators
     Conglomerate composition as an indicator of source direction

Environment of sedimentary accumulation

References cited

PLATE

1. Map and structure section of the Copper Harbor Conglomerate on Isle Royale, Michigan (omitted from the online edition)

FIGURE

1. Sketch map showing generalized distribution of Keweenawan rocks in the Lake Superior region

2. Chart showing nomenclature for middle and upper Keweenawan rocks of northern Michigan and adjacent parts of Wisconsin

3. Sketch map showing distribution of the Copper Harbor Conglomerate and paleocurrent directions on the Northern Peninsula of Michigan

4. Stratigraphic diagram of the Copper Harbor Conglomerate on Isle Royale from Rainbow Point to Francis Point

5—13. Photographs showing:

5. Boulder and cobble conglomerate at Cumberland Point

6. Pebble conglomerate overlying basalt on Hat Island in Malone Bay

7. Sandstone overlying basalt at small cove north of Schooner Island

8. Cobble conglomerate facies and pebble conglomerate facies on west end of Feldtmann Ridge

9. Sandstone facies on Stone House Island

10. Longitudinal section of trough-type crossbedding in sandstone on the southern side of Houghton Ridge

11. Cuspate ripple markings in sandstone on shoreline in sec. 18, T. 63 N., R. 37 W

12. Asymmetric ripple markings in sandstone on shoreline south of Fishermans Home Cove

13. Current-crescent structures in sandstone on shoreline south of Fishermans Home Cove

14. Map of sediment dispersal patterns in the Copper Harbor Conglomerate on Isle Royale

15. Photograph of desiccation cracks in fine-grained sedimentary rock on Menagerie Island

TABLE

1. Composition of pebble conglomerate

2. Composition of coarse to very coarse grained sandstone

3. Composition of very fine to fine grained sandstone

4. Composition of very fine grained sandstones, very coarse grained sandstones, and pebble conglomerates taken from the measured section on Houghton Ridge

5. Relative abundance of sedimentary features in sandstone and pebble conglomerate in the Copper Harbor Conglomerate, Isle Royale

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UNITED STATES DEPARTMENT OF THE INTERIOR
ROGERS C. B. MORTON, Secretary

GEOLOGICAL SURVEY
V. E. McKelvey, Director

Library of Congres catalog-card No. 73-6000388.

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