Pre-Tertiary metamorphic rocks, Jurassic granitic intrusions,
and Eocene basalts are exposed along the North Fork of the John Day
River at its confluence with Granite Creek. Geochemical and textural
evidence suggest greenschist-metamorphosed, strongly sheared,
volcanogenic rocks originated in an island-arc environment. These
greenstones were apparently intruded during the Late Permian...
The western part of the Late Cretaceous Nanaimo Basin
is exposed on Vancouver Island at Nanaimo, British Columbia.
The five lowest members of the Nanaimo Group are present
and represent a complete sedimentary cycle. The two lowest
formations, the Comox and Haslam, represent the marine part
of the cycle. The...
The Middle and West Forks of Little Sheep Creek in the southern Tendoy Range have incised valleys across Cenozoic structural features exposing strata that range in age from the Mississippian to the Neoene. Paleozoic strata are 1,349 m thick and belong to the Mission Canyon Limestone, the Big Snowy, Amsden,...
Approximately 4,210 feet of Late Cretaceous and 1,440 feet of Tertiary sedimentary rocks are exposed in the Salt Wells Anticline area of southcentral Sweetwater County, Wyoming. Late Cretaceous units include the Blair, Rock Springs, Ericson, and Almond Formations of the Mesaverde Group and the Lewis Shale; Tertiary units include the...
Approximately 23 square miles of the east-central part
of the Tendoy Range are included in the thesis area which
lies three miles west of Dell, Montana.
Rocks ranging in age from Late Mississippian to Recent
are exposed in the study area. The upper Paleozoic section
includes approximately 4,200 feet (1,281...
Clastic sedimentary rocks of the Nanaimo Group on Saltspring Island, British Columbia are Late Cretaceous in age, overlie a deformed and intruded Paleozoic basement complex, and consist of
eight formations. These eight formations, from oldest to youngest, are the Comox, Haslam, Extension-Protection, Cedar District, De Courcy, Northumberland, Geoffrey, and Spray...
The bedrock of Thetis, Kuper, and seven adjacent islands and
islets of British Columbia's Gulf Islands consists of four Late Cretaceous
(Campanian) formations of the Nanaimo Group. The four, from
oldest to youngest, are the Cedar District, De Courcy, Northumberland,
and Geoffrey Formations.
The formations vary greatly in thickness but...
The bedrock of North and South Pender Islands, the southernmost islands of British Columbia's Gulf Islands chain, is formed entirely by six formations of the Late Cretaceous Nanaimo Group. These six formations are, from oldest to youngest, the Extens ion- Protection, Cedar District, DeCourcy, Northumberland, Geoffrey, and Spray Formations, A...
During the Late Mississippian-Early Pennsylvanian (latest
Chesterian-early Morrowan), a thick sequence of shallow -water
carbonate-clastic sediments, equivalent to the "Amsden" and lower
Quadrant Formations, was deposited in the Snowcrest trough on the
western margin of the northern Rocky Mountain Cordilleran platform
in southwestern Montana. Today this late Chesterian sequence is...