1978/01/01 by G.N. Pipiringos, R. B. O'Sullivan · 245 citations
Earth and Planetary Sciences · Computer Science · #Geological Studies and Exploration #Geochemistry and Geologic Mapping #Paleontology and Stratigraphy of Fossils #Unconformity #Geology #Paleontology #Plateau (mathematics) #Colorado plateau #Archaeology #Sedimentary rock #Geography #Geochemistry
paper · pdf · doi:10.3133/pp1035a
published in USGS professional paper (United States Government Publishing Office)
openalex publication_date 1978/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The Triassic and Jurassic rocks in Western Interior United States contain nine unconformities each of which was destroyed to some extent by a younger unconformity. Regardless of extent, all are useful for correlation of rock sequences in areas where fossils or age dates are lacking. The purpose of this report is to call attention to the presence, significance, and value for correlation of these unconformities. The Triassic unconformities are designated from oldest to youngest, Tr-1, Tr-2, and Tr-3; the Jurassic ones similarly are designated J-0, J-l, J-2, J-3, J-4, and J-5. Of these, the J-2 surface is the best preserved and most widespread. It extends throughout the Western Interior and truncates the older unconformities in different parts of this area. Consequently, the J-2 surface is discussed and illustrated in much more detail than the others.