CROSS-BEDDING IN THE WHITE RIVER FORMATION 
OF NORTHWESTERN SOUTH DAKOTA 
DEAN E. WINCHESTER 
United States Geological Survey 
Rocks of White River (Oligocene) age have been known for 
many years to constitute numerous isolated buttes and mesas in 
the northwest corner of South Dakota, but no detailed study of 
their character and structural relations had been made until 1911, 
when, during an examination of the lignite area of that country, 
the writer had occasion to study the relation of the younes: rocks 
to those containing lignite beds. 
Todd, in 1895, recognized the White River formation in the 
Slim Buttes and called attention to the area in the following 
language: 
3. Miocene beds, both White River and Loup Fork, with characteristic 
fossils, have been found overlying wide areas of the Laramie north of the Black 
Hills, covering quite deeply most of Harding County, with thin outliers over the 
north half of Butte County and south half of Ewing. In the Short Pine hills 
and Slim Buttes these deposits exhibit a depth of 200 to 400 feet with character- 
istic fossil features closely resembling those of the White River region. 
4. An area of disturbance was found in the north half of Slim Buttes in 
northeast Harding County covering perhaps 20 to 25 square miles. This con- 
sists of sharp folds, including the Laramie and White River beds, with throws 
of perhaps too feet and dips of 25 degrees. 
It is the purpose of this paper to show that the inclination of 
beds described above, as well as those exposed at several other 
localities in the Slim Buttes, is not a true dip due to a dynamic dis- 
turbance but is cross-bedding due to the peculiar manner of the 
accumulation of the White River formation. 
White River beds, showing similar inclinations, are well exposed 
in at least three widely separated localities along the east side of the 
tJ. E. Todd, “Recent Geologic Work in South Dakota,” Am. Geologist, XVI 
(1895), 202. 
55° 
