7.4 SOUTH PARK
South Park is a north-south trending, elongated, intermontane basin located in Park County in central Colorado. The basin is approximately 45 miles long and 20 miles wide, encompassing some 893 square miles. South Park is a high-altitude, relatively flat, treeless plain located between the Mosquito Range and the Front Range (Figure 7.4-1). It is traversed by several ridges that rise hundreds of feet above the floor of the Park and extend for a number of miles down the center of the basin (e.g. Red Hill and Reinecker Ridge).
South Park is a structural basin with a major synclinal axis that plunges southward. The basin is broken on the east side by the Elkhorn Thrust, which brings pre-Cambrian rocks east of the fault against Tertiary and older rocks on the west. With the exception of the pre-Cambrian, all geologic formations exposed in the lower elevations of South Park are post-Mississippian in age. The geology of South Park is further complicated by igneous activity, generally of Tertiary age.
The South Platte River and its tributaries including Tarryall Creek drain South Park. Tarryall Creek and its tributaries drain the northern portion of the Park, while the South Platte River and its tributaries drain the remainder of the Park. South Park falls into the management of Water Division 1 with offices located in Greeley. South Park encompasses about 40 percent of Park County’s total area, whose population density in 2000 was about seven persons per square mile.