GEOLEX

Summary of Citation: Ogallala

Publication:
Darton, N.H., 1899, Preliminary report on the geology and water
   resources of Nebraska west of the one hundred and third
   meridian: U.S. Geological Survey Annual Report, 19, p.
   721-785

Usage in Publication:
Ogallala formation*

Modifications:	Geologic Province:	Dominant Lithology:
Named	Denver basin Chadron arch	Grit Limestone Clay Sand Conglomerate

Summary:
Named for development in western part of NE around Lodgepole Creek and area between Platte River and KS line west of 99th meridian. Thins out in Banner Co and central part of Cheyenne Co. Present in western part of Deuel Co. These areas lie within the Denver basin. Shown on geologic map as present eastward in Perkins, Lincoln, Chase, Hayes, Dundy, Hitchcock, and Red Willow Cos, NE on the Chadron arch. Cross sections. Neither source of name nor type locality stated. Composed of calcareous grit or soft limestone containing a greater or lesser amount of interbedded and intermixed clay and sand with pebbles of crystalline rocks and a basal conglomerate bed. Thickness of 150 to 300 ft. Is younger than Arikaree formation. Overlies Brule clay. Shown on geologic map as of Tertiary age, though age of Ogallala not discussed. Was considered part of Loup Fork formation [in earlier reports?-not clear]. Many photographs. Many columnar diagrams.

Summary of Citation: Ogallala

Publication:
Denson, N.M., 1965, Miocene and Pliocene rocks of central Wyoming,
   IN Cohee, G.V., and West, W.S., Changes in stratigraphic
   nomenclature by the U.S. Geological Survey, 1964: U.S.
   Geological Survey Bulletin, 1224-A, p. A70-A74

Usage in Publication:
Ogallala Formation*

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits	Wind River basin

Summary:
Used for upper Miocene and Pliocene rocks in Granite Mountains area, Fremont and Natrona Cos, WY in the Wind River basin as the unit above Arikaree Formation in preference to Split Rock Formation. Term Split Rock abandoned.

Summary of Citation: Ogallala

Publication:
Barnes, V.E., 1967, Geologic atlas of Texas, Lubbock Sheet;
   Halbert Pleasant Bybee memorial edition: University of
   Texas-Austin, Bureau of Economic Geology, 1 sheet, scale
   1:250,000

Usage in Publication:
Ogallala Formation

Modifications:	Geologic Province:	Dominant Lithology:
Overview	Palo Duro basin Permian basin	Sand Silt Clay Gravel Caliche

Summary:
Is Pliocene formation mapped in western and north-central part of map sheet. Is mapped as mostly continuous belt along the Caprock Escarpment, as well as along stream drainages on the Llano Estacado in southern Hale, southern Floyd, and southwest Motley Cos, TX (Palo Duro basin) and Lubbock, Crosby, northwest Dickens, Lynn, and western Garza Cos, TX (northeastern Permian basin). Comprised of Bridwell and Couch Members, not separately mapped. Map unit described as fluviatile sand, silt, clay, and gravel capped by caliche. Sand, fine- to medium-grained quartz, in part silty and calcareous, clayey in upper part, clayballs, indistinctly bedded to massive, cross-bedded, unconsolidated to weakly cohesive, local quartzite lenses, various shades of gray and red. Silt and clay with caliche nodules, reddish brown, dusky red, pink. Gravel, not everywhere present, mostly quartz, some quartzite, sandstone, limestone, chert, igneous rock, metamorphic rock, and worn GRYPHAEA in intraformational channel deposits and in basal conglomerate. Caliche, sandy, pisolitic at top, hard, forms caprock. Fossil plants and vertebrates scarce. Maximum thickness 250 ft.

Summary of Citation: Ogallala

Publication:
Harksen, J.C. and Green, M., 1971, Thin Elk Formation, lower
   Pliocene, South Dakota: South Dakota Geological Survey Report
   of Investigations, no. 100, 7 p.

Usage in Publication:
Ogallala Group

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Sioux uplift

Summary:
Upper contact revised in that Thin Elk Formation, a new formation above Rosebud Formation of Ogallala Group named in Millette Co, SD on the Sioux uplift. Thin Elk is a stream deposit that cut into the Rosebud. Thin Elk-Rosebud contact chosen at lithologic change from pink silt of Rosebud to yellowish to brownish sand and gravel of Thin Elk. Of early middle Oligocene age.

Summary of Citation: Ogallala

Publication:
Bachman, G.O., 1976, Cenozoic deposits of southeastern New Mexico
   and an outline of the history of evaporite dissolution: U.S.
   Geological Survey Journal of Research, v. 4, no. 2, p.
   135-149

Usage in Publication:
Ogallala Formation*

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits Overview	Permian basin

Summary:
Is the oldest record of Tertiary history and climate preserved in southeastern NM. Is mapped (fig 2) in southern Lea Co and eastern Eddy Co, NM in the Permian basin. It underlies the High Plains and is well exposed along Mescalero Ridge where it typically includes three units (descending): 1) caliche (caprock), brecciated, light-gray to white, densely pisolitic in upper part, 8-10 ft thick; 2) sand, light-brown, fine grained; grains are mostly quartz, subangular to well rounded, and well sorted, 6.5-14 ft thick; 3) sand, very friable, moderate orange-pink to grayish-orange-pink, fine grained; grains are mostly quartz, well rounded, and well sorted, strongly cross laminated locally, 16-20 ft thick. Base is commonly covered. Much of Ogallala in eastern NM was deposited on irregular erosional surface as a series of complex alluvial fans. High Plains surface in southeastern NM slopes southeastward about 10 ft/ mi and this slope is presumed to reflect original depositional surface. Ogallala thins towards the south and southwest from the High Plains: 315-345 ft thick along Mescalero Ridge north of Maljamar, 100-180 ft thick at Hat Mesa, and no more than 27 ft thick on west side of The Divide. Pisolitic caliche caps the Ogallala at all of these localities indicating that thinning occurred before caliche formed. Age is given as Miocene and Pliocene.

Summary of Citation: Ogallala

Publication:
Barnes, V.E., 1976, Geologic atlas of Texas, Hobbs Sheet; William
   Battle Phillips memorial edition: University of Texas-Austin,
   Bureau of Economic Geology, 1 sheet, scale 1:250,000

Usage in Publication:
Ogallala Formation

Modifications:	Geologic Province:	Dominant Lithology:
Overview	Permian basin	Sand Silt Clay Gravel Caliche Conglomerate

Summary:
Is Pliocene formation mapped discontinuously across most of map sheet in southeast NM and western TX (Permian basin). Map unit described as fluviatile sand, silt, clay, and gravel capped by caliche. Sand, fine- to medium-grained quartz, in part silty and calcareous, clay balls common, clayey in upper part, indistinctly bedded to massive, cross-bedded, unconsolidated to weakly cohesive, local quartzite lenses, various shades of gray, red. Silt and clay with caliche nodules, reddish brown, dusky red, pink. Gravel, not everywhere present, mostly quartz, some quartzite, sandstone, limestone, chert, igneous and metamorphic rock, and worn GRYPHAEA in intraformational channel deposits and in basal conglomerate. Caliche, sandy, pisolitic at top, hard, produces caprock along Mescalero Ridge, may have formed since the Pliocene. Fossil plants and vertebrates scarce. Maximum thickness up to 100 ft.

Summary of Citation: Ogallala

Publication:
Skinner, M.F., Skinner, S.M. and Gooris, R.J., 1977, Stratigraphy
   and biostratigraphy of late Cenozoic deposits in central
   Sioux County, western Nebraska: American Museum of Natural
   History Bulletin, v. 158, art. 5, p. 263-370

Usage in Publication:
Ogallala Group

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Denver basin

Summary:
Snake River Formation of the Ogallala Group in the Denver basin is restricted to deposits that disconformably overlie the Olcott Formation (new) of the Hemingford Group and other rocks, and contain early and late Clarendonian faunas, early Hemphillian Aphelops Draw fauna, and late Hemphillian ZX Bar local fauna. Matthew (1924) divided his "Snake Creek beds" into 2 faunal zones without regard to lithology. The lower Snake Creek faunal zone is carried in the Olcott Formation (new) of the Hemingford Group (revised). The upper Snake Creek faunal zone is carried in the Snake Creek Formation (revised) of the Ogallala Group (revised). As revised, the Snake Creek contains three new members (ascending): Murphy, Laucomer, and Johnson Members. Johnson Member is top of section in central Sioux Co, NE study area. Age of Ogallala present in study area is Clarendonian (middle Miocene) and Hemphillian (late Miocene) based on vertebrate faunas.

Summary of Citation: Ogallala

Publication:
Barnes, V.E., 1983, Geologic atlas of Texas, Tucumcari Sheet;
   Henryk Bronislaw Stenzel memorial edition: University of
   Texas-Austin, Bureau of Economic Geology, 1 sheet, scale
   1:250,000

Usage in Publication:
Ogallala Formation

Modifications:	Geologic Province:	Dominant Lithology:
Overview	Sierra Grande uplift Amarillo arch Palo Duro basin	Sand Caliche Gravel

Summary:
Is Pliocene formation mapped discontinuously across most of the map sheet in northeastern NM and TX panhandle. Is mapped in Harding and Union Cos, NM (Sierra Grande uplift); Moore and Potter Cos, TX (Amarillo arch); and San Miguel and Quay Cos, NM and Hartley, Oldham, Deaf Smith, and Randall Cos, TX (Palo Duro basin). Map unit described as sand, silt, clay, gravel, and caliche. Sand, fine- to coarse-grained quartz, silty in part, caliche nodules locally, cemented locally by calcite and by silica, locally cross-bedded, various shades of gray, brown, and red. Minor silt and clay with caliche nodules, sandy in places, massive, white, gray, olive-green, brown, red, and maroon. Gravel, not everywhere present, composed of pebbles and cobbles of quartz, quartzite, minor chert, igneous rock, metamorphic rock, and clay balls in lower part. Caliche, not everywhere present, sandy, pisolitic, white, gray, pink, may include some caliche of Pleistocene age; thickness up to about 400 ft.

Summary of Citation: Ogallala

Publication:
Swinehart, J.B. and Diffendal, R.F., Jr., 1997, Geologic map of
   the Scottsbluff 1 degrees x 2 degrees quadrangle, Nebraska
   and Colorado: U.S. Geological Survey Miscellaneous Investigations
   Series Map, I-2545, 1 sheet, scale 1:250,000

Usage in Publication:
Ogallala Group*

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:250k (Scottsbluff quad, NE)	Denver basin Chadron arch	Sand Gravel Sandstone Siltstone Conglomerate

Summary:
Mapped as upper and middle Miocene group in western NE (Denver basin and Chadron arch). Unit described as principally fluvial deposits. Divided into three units (not separately mapped, though separately described) (descending): informal Angora sand and gravel beds (upper Miocene) of Swinehart and Diffendal (in press, USGS Map I-2496), Ash Hollow Formation (upper Miocene), and informal Duer Ranch beds (middle Miocene) of Swinehart and Diffendal (1987, GSA Centennial field guides, v. 3, p. 23-28). Consists of sand and gravel and interbeds of silt and diatomite of Angora; sandstone, pebbly sandstone, and siltstone, gravel and sand, diatomite, volcanic ash, and calcrete and silcrete of Ash Hollow; silty sandstone, lesser amounts of siltstone and conglomerate, and some colluvium of Duer Ranch. Only Ash Hollow crops out widely south of North Platte valley; other units have limited outcrops. Deposits commonly fill paleovalleys. Map unit locally includes areas of post-Ogallala deposits and older bedrock units too small to map separately. Underlies Broadwater Formation (Pliocene); overlies Arikaree Group (lower Miocene and upper Oligocene).