Date of Award


Document Type


Degree Name

Master of Science (MS)



First Advisor

L. Clayton


The Quaternary stratigraphy of central North Dakota is best exposed along the nearly continuous, 20-meter-high, vertical bluffs of Lake Sakakawea in the Missouri River trench. The following lithostratigraphic units (in ascending order) are exposed just north of Riverdale, North Dakota, and can be correlated for tens of kilometers along the bluffs: (1) Sentinel Butte Formation (lignite-bearing sediment of Paleocene age), (2) lower Medicine Hill Formation (fluvial sand and gravel), (3) upper Medicine Hill Formation (massive pebble loam with silt and gravel inclusions> glacial sediment), (4) lower Horseshoe Valley Formation (fluvial sand and gravel), (5) upper Horseshoe Valley Formation (jointed pebble-loam, glacial sediment), (6) lower Snow School Formation (fluvial sand and gravel), (7) mid dle Snow School Formation (reddish sandy pebble-loam, glacial sediment), (8) upper Snow School Formation (jointed pebble-loam, glacial sediment, (9) Oahe Formation with four numbers recognize able throughout the area (silt, eolian sediment).

The sand bodies are the main aquifers in the Lake Sakakawea groundwater discharge area.

Included in

Geology Commons