Contributions to Geology 16.2

Magnetic prospecting for roll front uranium deposits in the Powder River Basin, Wyoming

ROBERT J. MACKENZIE and PETER N. SHIVE Department of Geology, The University of Wyoming, Laramie, Wyoming 82071

Pages
67-78

Keywords
roll front, uranium, Powder River, Wyoming, magnetic

Abstract
In order to test the possibility of detecting roll front uranium deposits in the southern part of the Powder River Basin of Wyoming by magnetic prospecting, a three part magnetic study was completed as follows: 1) A regional ground magnetic map of an 1800 square mile area in the basin was used to establish regional gradients in areas of detailed study, 2) Induced and remanent magnetic property measurements on 116 samples from mineralized areas showed that magnetization contrasts do not exceed 5x10-5 emu/cc, but that a stable remanence of significantly greater intensity could be carried by the samples, 3) A detailed ground magnetic survey over an area known to contain roll fronts showed anomalies from shallow sources no greater than three gammas in amplitude. Magnetic prospecting for roll front deposits is not recommended unless future studies indicate 1) that other roll front areas are associated with magnetization contrasts at least an order of magnitude greater than those of our samples, and 2) that the magnetic background in the basin is smooth enough to permit resolution of small anomalies possibly associated with roll fronts.

Revised and amended fossil vertebrate faunal lists, Early Tertiary, Hoback Basin, Wyoming

JOHN A. DORR, JR. Department of Geology and Mineralogy, The University of Michigan, Ann Arbor, Michigan 48109

Pages
79-84

Keywords
fossil, vertebrate, Tertiary, Hoback Basin, Wyoming, plants, pollen

Abstract
Datable, Early Tertiary fossil vertebrates, mostly mammals, have been found at twelve localities in the Hoback Basin, central western Wyoming. Revised and amended lists of taxa from each locality are provided, in stratigraphic order. The faunules range in age from Middle Tiffanian (Middle Late Paleocene) into Late Wasatchian (Late Early Eocene). Fossil plants, mostly pollen, and invertebrates, are associated with the vertebrates at some localities. The fossils came from the following stratigraphic units: Hoback Formation, Chappo Member of the Wasatch Formation, Lookout Mountain Conglomerate Member of the Wasatch Formation, and the Pass Peak Formation.

Sample preparation for strontium analysis of ancient skeletal remains

ANTOINETTE B. BROWN Department of Anthropology, California State University, Los Angeles; Los Angeles, California 90032
HENDRIK KEYZER Department of Chemistry, California State University, Los Angeles; Los Angeles, California 90032

Pages
85-88

Keywords
strontium, archeological, sample preparation

Abstract
Two techniques novel to archeological bone strontium analysis have been applied to field test samples. A standardized routine procedure is presented involving ultrasonic cleaning and microwave wet ashing in HNO3 followed by HClO4 which can easily cope with 100 mg total available sample of bone by means of conventional atomic absorption analysis. Such results obtained more rapidly and conveniently, and expressed per dry weight, have increased reliability and accuracy.

Test porosity as a paleoenvironmental tool in the Late Cretaceous of the Western Interior

WILLIAM E. FRERICHS and ROBERT ELY Department of Geology, The University of Wyoming, Laramie, Wyoming 82071 Laramie, Wyoming 82071

Pages
89-94

Keywords
porosity, Cretaceous, Western Interior, Hedbergella amabilis, Rotalipora cushmani

Abstract
Test porosities and pore densities of specimens of Hedbergella amabilis and Rotalipora cushmani indicate that these parameters may be used as paleoenvironmental indicators in the Late Cretaceous. These parameters are greatest in specimens of these two species from the Eagle Ford Formation of Texas. Distinctly smaller values were noted in specimens from the Greenhorn Formation of the Western Interior. In the Western Interior larger values of these parameters were found on the western side of the seaway and indicate that a northward flowing warm current was present on this side of the seaway.

An American lion, Panthera atrox, from Natural trap cave, north central Wyoming

LARRY D. MARTIN Museum of Natural History and Department of Systematics and Ecology, University of Kansas, Lawrence, Kansas 66045
B. MILES GILBERT American Archaeology Division, University of Missouri-Columbia, Columbia, Missouri 65201

Pages
95-102

Keywords
Panthera atrox, lion, Wyoming

Abstract
Natural trap cave has produced a diverse fauna of Pleistocene mammals indicative of both forest and open country. However, cursorial large mammals dominate the fauna. The most spectacular of these is the cheetah-like cat, "Felis" trumani. We can now add the American lion, Panthera atrox, and argue that it too was a "running cat".

Animal tracks in the Navajo-Nugget Sandstone

WM. LEE STOKES Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112

Pages
103-108

Keywords
tracks, Navajo, Nugget, ichnofossils, vertebrates, invertebrates

Abstract
A considerable number of localities in the Navajo-Nugget Sandstone have yielded ichnofossils. Both invertebrates and vertebrates are represented. Localities known to the writer and described in this paper include: 1) East slope of the Wind River Mountains near Wyoming Highway 28; 2) Indian Creek, near Bear Lake, Idaho; 3) Stone quarries near Heber, Utah; 4) Long Ridge, Juab County, Utah; 5) Flag Creek, near Meeker, Colorado; 6) Buckhorn Draw, Emery County, Utah; 7) Devils Canyon, Emery County, Utah; 8) San Rafael Reef, Emery County, Utah; 9) Near Dolores River-Colorado River junction, Utah; 10) Sand Wash, Grand County, Utah; 11) Escalante-Boulder road near Escalante River, Utah; and 12) Glen Canyon Dam on the Colorado River, Arizona.

None of these occurrences is incompatible with the theory of a nonmarine origin for the Navajo-Nugget Sandstone.