Judith River Group
Encyclopedia
The Judith River Group is a group of geologic
formations in western North America
dating from the late Cretaceous
and noted as a site for the extensive excavation of dinosaur
fossils. The formation is named after the Judith River
in Montana
. The group is also called the Judith River Wedge. It is stratigraphically equivalent with the Belly River Group
in Alberta
.
It comprises the Judith River Formation
in north central Montana, as well as the Foremost
, Oldman
, and Dinosaur Park
formations in Alberta
and Saskatchewan
in Canada
. Within Canada, the name term Belly River Group is more widely used for what is essentially the same stratigraphic interval as the Judith River. The wedge is exposed discontinuously in river drainages.
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
formations in western North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
dating from the late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
and noted as a site for the extensive excavation of dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
fossils. The formation is named after the Judith River
Judith River
The Judith River is a tributary of the Missouri River, approximately 124 mi long, running through central Montana and the United States. It rises in the Little Belt Mountains and flows northeast past Utica and Hobson...
in Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
. The group is also called the Judith River Wedge. It is stratigraphically equivalent with the Belly River Group
Belly River Group
The Belly River Formation is a stratigraphical unit of Late Cretaceous age in the Western Canadian Sedimentary Basin.It takes the name from the Belly River, a tributary of the Oldman River in southern Alberta, and was first described in outcrop on the banks of the Oldman River and Bow River by...
in Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
.
It comprises the Judith River Formation
Judith River Formation
The Judith River Formation is a fossil-bearing geologic formation in Montana, and is part of the Judith River Group. It dates to the upper Cretaceous, between 80 and 75 million years ago, corresponding to the "Judithian" land vertebrate age...
in north central Montana, as well as the Foremost
Foremost Formation
The Foremost Formation is a geological formation in Alberta, Canada whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.-Dinosaurs:...
, Oldman
Oldman Formation
The Oldman Formation is the middle member of the Judith River Group, a major geologic unit in southern Alberta. The formation is widely recognized as bearing a great number of well preserved dinosaur skeletons, as well as other fossils.-Age:...
, and Dinosaur Park
Dinosaur Park Formation
The Dinosaur Park Formation is the uppermost member of the Judith River Group, a major geologic unit in southern Alberta. It was laid down over a period of time between about 76.5 and 75 million years ago. The formation is made up of deposits of a high-sinuosity fluvial system, and is capped...
formations in Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
and Saskatchewan
Saskatchewan
Saskatchewan is a prairie province in Canada, which has an area of . Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota....
in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. Within Canada, the name term Belly River Group is more widely used for what is essentially the same stratigraphic interval as the Judith River. The wedge is exposed discontinuously in river drainages.