GEOLOGY

Nearly the entire surface of Cavalier County consists of gently rolling to undulating terrain and is underlain by sediment deposited during the last advance of glaciers into the Rendezvous Region about 12,000 years ago.  Subtle land forms were produced by these glaciers.  The Pembina Escarpment, along the eastern edge of Cavalier County, marks the eastern edge of this glaciated plain.
	East of the escarpment is the Red River Valley, which is the former floor of glacial Lake Agassiz that occupied the valley about 11,000 years ago.  The extremely flat Lake Agassiz basin terrain of Pembina County, one of the flattest areas in the world, is interrupted in the western part of the county by low, elongate hills that were Lake Agassiz beaches.  Cretaceous age rock that underlie the glacial deposits in the Rendezvous Region are exposed where river, primarily the Pembina River and its tributaries, have cut through the glacial deposits, primarily in the Pembina Gorge.
These Cretaceous rocks were deposited in oceans that covered the area between about 90 million and 80 million years ago.  The rocks contain fossils of the animals that lived in those oceans.