The mountains consist primarily of sedimentary rock, limestone, sandstone and shale, of Jurassic, Cretaceous and Paleogene origin on a Precambrian granitic basement.
Geologists refer to them as tilted-block fault mountains and in them can be found billion-year-old Precambrian rocks, the oldest in Texas.
He also is remembered for his studies of Precambrian and Paleozoic rocks of the Grand Canyon and as the first to prepare a detailed geologic map of a large part of Grand Canyon National Park.
The massive steep-sided volcano of dominantly basaltic-to-trachybasaltic composition forms a volcanic horst constructed above a basement of Precambrian metamorphic rocks covered with Cretaceous to Quaternary sediments.
The diamictite sedimentary deposits of the mountain, several kilometers thick, date to the late Precambrian and probably have a glacial-marine origin.
It is only known from three localities in the semideciduous forests of the Precambrian Brazilian shield of western Brazil and eastern Bolivia.
Most of the area is dolomitic (Precambrian) and the district was in the past renowned for its mineral wealth.
The geology of the Planet area is ancient, estimated to be Precambrian, the bedrock being made up mostly of pinkish gneiss and absorbed limestone and amphibolite, which contained hematite-copper.
The Winterburn Group is conformably overlain by the Wabamun Group and overlays the Ireton Formation, except in the Peace River Arch, where it rests on the Precambrian basement.
It has a long history of movement with early ductile fabrics preserved from a sinistral (left lateral) strike-slip sense shear zone active at the end of the Precambrian and into the early Cambrian.
While Bexley lies almost entirely within the Paleozoic limestone region of southern Ontario, the small portion of the Gull River valley north of Silver Lake lying within the township is within the Precambrian Canadian Shield region.
He mapped the movements of Vancouver Island and other parts of the Cordillera that have moved sideways and rotated relative to the Precambrian Canadian Shield.
Among his contributions were studies in the military uses of optical glass; physical study of lunar features based on the properties of the reflected light, and the precambrian geology of the region near Lake Superior.
This fault zone directly overlies a granite "high" in the Precambrian basement and is structurally active as the Humboldt Fault.
He specializes in the Precambrian era and is widely known for the theory of the Snowball Earth about phenomena that occurred in the Neoproterozoic era, co-published with Daniel P. Schrag.
Apart from doing structural field studies in varied terrain, including the Precambrian structures of Peninsular India, the Scottish Highlands, the Scandinavian Caledonides and East Antarctica.
He also established linkages with some leading geochemists outside the country and, among many other projects, led, with John A. Rogers of the University of North Carolina, Chapel Hill, a highly-praised Indo-US collaborative programme on Precambrians of South India.