Clovis Period

Time: The oldest period of human occupation at the Landmark is the Clovis Period, and dates from 11,500 to 11,000 years ago.

Sediments: Gravel and sand was deposited by a meandering stream that wove through the draw. The stream stopped flowing rather abruptly around 11,000 to 10,800 years ago, and the draw, up to 8 meters deep in places, began to fill slowly. During this time, the stream was surrounded by marshy meadow lands and a parkland capable of supporting herds of large grazing animals. The climate was probably that of frost-free winters and cooler summers.

Plants: Surrounded by marshy meadow lands in the draw, phytolith (grass fossils) evidence and unidentified grass seeds suggest that the draw was a parkland with grasses capable of supporting herds of large grazing animals. Seepweed (Suada sp.) existed in the scrub grassland areas and probably lined the edge of the draw preferring the more alkaline soils upstream. Prairie dog communities suggest short grass prairie areas. Bulrush (Scirpus spp.) and spike rush (Eleocharis spp.), two water plants, provided abundant vegetation for fish, ducks, water mammals, and herptiles in the marshy and stream areas. Along the valley floor, scattered small groves of netleaf hackberry (Celtis reticulata) grew along with gromwell (Lithospermum spp.). Beyond the local environmental conditions, the climate was probably that of frost-free winters and cooler summers.

 

Folsom, Firstview & Plainview Periods

Time: Folsom - 10,800 to 10,300 years ago Plainview - 10,000 years ago Firstview - 8,600 years ago

Sediments: The sediments are mostly marsh deposits. Some contain beds of pure diatomite (fossil remains of unicellular algae), that represent periods of standing water, and peaty muds with few diatoms but abundant phytoliths, interpreted as periods when water was just below the surface. A series of clear-water ponds were interconnected by a low volume stream that kept fresh water flowing through the valley floor.

Mild winters with periods of freezing temperatures persisted though summers were warming. The prairie habitat became dominant in the draw environment, indicating a decrease in available moisture and humidity levels with periodic summer droughts. The valley floor was a wet meadow marshlands that graded into an open prairie.

Soil named Firstview Soil developed from about 8,500 to 6,300 years ago with high organic content in the marshy areas and less so in other areas. The soil formed in a boggy area with a water table close to or occasionally at the surface but without expanses of water of any depth.

Plants:

Folsom and Plainview Periods
Although two distinct cultural periods, the Folsom and Plainview periods are fairly similar environmentally. A series of clear-water ponds with weedy growth (Chara spp.) were interconnected by a low volume stream that kept fresh water flowing through the valley floor surrounded by sedge beds and rushes. The amount of wooded areas decreased from a parkland to a savanna of occasional hackberry trees. Open grasslands increased including shortgrass prairie areas. Sandy slopewash areas supported gaura (Gaura sp.), devil's claw (Proboscidea louisianica), goosefoot (Chenopodiaceae), and buffalo bur (Solanum rostratum). The prairie habitat became dominant in the draw environment.

Firstview Period 8,600 years ago
By the Firstview Period, the valley floor was a wet meadow marshlands that graded into an open prairie. The marshland was a boggy area with a water table close to or occasionally at the surface but without expanses of water of any depth. Moist, tall grass cover, sedge beds, and cattails (Typha spp.) surrounded the marsh. Prairie habitat continued to dominate the draw. Areas of brushland and areas of very sparse vegetation indicate scrub grasslands habitat. A transitional period from a mixed prairie to a desert plains grasslands, the introduction of the southwestern floral element reflects the increasing warming and drying trend. Yearly precipitation was decreasing with a shift in rainfall pattern and periodic summer droughts although shallow surface water resources was present.