Published by the American Geophysical Union as part of the Field Trip Guidebooks Series, Volume 115/315.
The scheduling of the International Geological Congress field trips T-115 and T-315 through the Grand Canyon during the summer of 1989 has provided an unparalleled opportunity not only to prepare detailed river trip logs describing geologic and hydraulic features that may be observed from Lees Ferry to Lake Mead, but also to compile a modern summary of Grand Canyon geology. To persons unfamiliar with details of the geology, it is commonly supposed that no major problems exist because of the superb and extensive exposures. One objective of this volume is to identify and place in perspective some of the salient problems that remain
- Geologic and hydraulic river trip logs (chapters 1 and 2) are designed to be used during a river trip through Marble Canyon and the Grand Canyon. These logs are followed by a review of hydraulic characteristics of the Colorado River (chapter 3). Physiographic, geologic, and structural settings, found in Chapters 4-7, serve as a general review for the geologist and non-geologist alike.
- Geologic characteristics of the Early Proterozoic crystalline basement, and of stratified and intrusive rocks of the Middle and Late Proterozoic Grand Canyon Supergroup, are summarized in Chapters 8-11.
Of particular interest is an interpretation that the Late Proterozoic Chuar Group accumulated mainly in a lacustrine rather than a marine environment of deposition, and that carbonaceous strata of the Chuar Group may have served as a potential source of Precambrian oil. A preliminary, stratigraphically controlled, apparent polar wandering path developed from Proterozoic and Paleozoic rocks of the Grand Canyon and environs is shown in Chapter 12; the polar path and polarity zonation lead to correlations with poles reported from Proterozoic rocks elsewhere in North America, and the character of the polar path may reflect the nature of movement of the North American plate with respect to episodes of tectonism.