The LoDaisKa Site is located beneath an outcrop of Fountain Sandstone,
about a mile south of Morrison, on the ranch of Otto Sanger.
Physiographically the Morrison area is part of the Southern Rocky
Mountain Province. Broad elevated strips of granite, running north
and south, are flanked by dipping sedimentary rocks. The latter are
generally lower and form foothills. Both once formed continuous
anticlinal structures, now deeply eroded (Fenneman, 1931). The granite
masses are usually mountainous, but occasionally form vast plateaus
such as South Park. Locally they are capped by remnant sedimentaries.
[Illustration: Courtesy U.S. Geological Survey
FIGURE 3—Morrison Biome, looking west. Central Ridge is the Hogback.
Note encroachment of trees along watercourses and at higher
elevations.]
For over half the mountain frontage of this Province, a very resistant
formation, the Dakota Sandstone, creates a “hogback”. A valley of
weaker sedimentaries lies between it and the foothills, beginning about
two miles to the west. The Fountain Sandstone, locally known as the
“Red Rocks” formation, outcrops in this depression.
Mountain streams collecting in the inter-ridge valley form a trellis
drainage pattern. Master streams cut through the Dakota Formation
creating watergaps. The LoDaisKa Site lies in the shelter of an outcrop
of the Fountain Sandstone which rises some 60 feet above the valley.
The site lies at an elevation of about 6200 feet.