Figure 12
Sergeant Major Creek Exposure #1, Section 35-13N-24W,
near the center of the Thurmond Ranch. This is a laminated stream deposit of
sediments derived almost entirely from the Ogallala Formation, the modern
outcrop edge of which lies 1.25 mi (2 km) to the south. The virtual absence of
Permian redbed clastics in this deposit indicates that the locality was within
the outcrop boundary of the Ogallala Fm. 17,000-15,000 years ago. In other
words, the Ogallala boundary has eroded over a mile to the south in the last
15,000 years. Like Brokenleg Bend #1, this profile stands some 70' (21 m) in
elevation above the modern creek.