GeoNewsNote: New GSA Field Guide on Colorado

Title: GeoNewsNote: New GSA Field Guide on Colorado

Author: Mark W. Longman

Publication: The Outcrop, January 2000, p. 12, 17-18

The Reverend John Walker, who taught the first systematic course in geology at the University of Edinburgh (1781-1803), said to his students: “The way to knowledge of natural history is to go to the fields, the mountains, the oceans, and observe, collect, identify, experiment, and study.” Two hundred years later his thought still has merit. It is in this spirit that the Geological Society of America (GSA) has begun a new series of Field Guides including summaries of field trips offered at conventions. In this same spirit, the editors David R. Lageson (Montana State University), Alan Lester (University of Colorado), and Bruce Trudgill (also CU) of this first new (Nov. 1999) Field Guide, titled “Colorado and Adjacent Areas,” dedicate their volume to those field-­based earth scientists of the twentieth century who walked the outcrops and paid their dues in the field.

The volume consists of 12 summaries of field trips offered in conjunction with the 1999 Annual GSA Convention held in Denver in October. Unfortunately, because of tight time constraints, not all field trips offered at the convention are included in this volume, but those that are here cover a wide variety of topics. The first paper by David Noe, James Soule, Jeffrey Hines, and Karen Berry, all with the Colorado Geological Survey, offers a very interesting and readable account of geologic hazards and engineering geology along Colorado’s Front Range. Their trip, which was run as an RMAG “On-the-­Rocks” trip this past September, included discussions of features along a circle route from Denver to Boulder, Golden, Morrison, and Littleton. Even those who have spent a lifetime in this area will learn much about how geology has contributed to problems in the construction of roads, mines, restaurants (e.g., Boulder’s “Stonehenge”), and homes.

Papers 2 and 3 in the volume, by Eric Erslev (Colorado State University) and several co-authors, focus on the structural geology of the northern Colorado Front Range. Careful field mapping and observations are critical to unraveling the complex structural history of this tectonic province. Paper #2 deals with the major Laramide thrust faults on the west flank of the Front Range (and the associated volcanic rocks and normal faults), and the east flank’s higher-angle thrust and reverse faults. Paper #3 deals mainly with basement-involved structures in the Fort Collins area.

Space limits a discussion of each of the remaining papers in the volume, but they focus on topics ranging from hydrogeology and wetlands in the foothills near Denver (K. E. Kolm and J. C. Emerick, CSM) and climate change recorded in eolian sediments of the High Plains of eastern Colorado (D. R. Muhs et al., USGS) to salt tectonics in the Eagle River valley (R.B. Scott et al., USGS) and the “Stratigraphy, sedimentation, and paleontology of the Cambrian-Ordovician in Colorado” (Paul Myrow et al., Colorado College). More specific topics covered in the volume include the Cretaceous/Tertiary boundary in the Raton Basin (C.L. Pillmore et al., USGS), sediments in Cave of the Winds near Manitou Springs (Luiszer, CU), coal mining in the Yampa coal field of northwestern Colorado (Brownfield et al., USGS), and famous vertebrate paleontologist George Simpson’s boyhood neighborhood in east Denver (Laporte, Univ. of California at Santa Cruz). The only paper dealing entirely with an area entirely adjacent to Colorado is a discussion of the Heart Mountain detachment in the northeast Absaroka Range of Wyoming by Malone (Illinois State Univ.) et al.

As a whole, these papers are well written and well edited. They contain much “meat” and merit about the areas under discussion. Black and white illustrations, particularly photos, geologic maps, and stratigraphic columns are numerous. The most amazing part of the volume is that GSA was able to get it into print so quickly in conjunction with the annual convention, and that they priced the 201-page, soft-cover volume at only $20 (member price; $25 non­members, plus postage and handling). Copies can be ordered from GSA’s web-site at http://www.geosociety.org or by calling the GSA at 1-800-472-1988.