History and Scientific Significance

Artifacts from the area reveal at least a transient population of native people.  The majority of the information comes from the areas near the junction of the Rio Grande and the Rio Conchos.  Even though anthropologists have attributed different tribes as occupying the area, including the Pueblo culture and the Anasazi, the Jumano had a continuous record from the 15^th to the 18^thcentury.

Toward the end of the 18^th century the Jumano culture disappeared.  What happened to them is still speculation.  It could have been from interbreeding with the Lipan-Apaches, or the Jumano could have been killed by the Apache, and there is evidence that the disease epidemics introduced by the Spaniards could have contributed to their demise (Thompson, 1985).

This area along with the majority of Trans Pecos of Texas was originally claimed by the Spanish and then the Mexican governments.  After the Texas War of Independence in 1836 much of this area of the state was in dispute.  The United States acquired Texas by annexation in 1845, but the Rio Grande as a boundary was not confirmed until the Treaty of Guadalupe Hidalgo was signed in 1848 (Nelson and Preston, 2006).

In 1850 the Chihuahuan Acquisition consisted of areas A, B, C, and D.  A – C dealt with land that became New Mexico and D covered land that established the following Texas counties:  El Paso, Hudspeth, Culberson Jeff Davis, Presidio and parts of Brewster, Pecos and Reeves (Bowden, 1971). The DDRS is a part of both Presidio and Brewster Counties.  After the Chihuahuan Acquisition of 1850, all the property was owned by the State of Texas.

In 1910 – 1912 Tom Rawls obtained much of the region including sections 541 and 542 from the State.  In 1916 these two sections were a part of a large land purchase by Mr. Pearl Andrew Jackson from Mr. Rawls.  The two sections remained property of his heirs until Dr. Dalquest purchased them in 1968.  Midwestern State University purchased 680 hectares (1,680 acres) of adjacent land from the State of Texas in 2004 to bring the total to approximately 1,200 hectares (3000 acres).

The majority of the site has had little human influence; in fact, the previous owners fenced the canyon lands to keep the cattle from getting into the area.

The diversity of flora on DDRS reflects the steep gradient in elevation between the uplands and canyon lands. On the uplands, the Chihuahuan desert indicator species lechuguilla (Agave lechuguilla) and tarbush (Florensia cernua) are associated with creosote bush (Larrea tridentata), ocotillo (Fouquieria splendens), plume tiquilia (Tiquilia greggii), yucca (Yucca spp.), sotol (Dasylirion leiophylla) and an array of cacti. In 2005 a 26-month survey of an upland 10,000 m² plot identified 86 species from 29 families, excluding grasses (Killion and Cook submitted). 

In the canyons, oak (Quercus grisea), walnut (Juglans spp.), juniper (Juniperus pinchotii) and woody legumes (Mimosa spp. and Acacia spp.) form dense pockets of woodland along intermittent waterways. Throughout the site, a variety of annual and perennial wildflowers mark the milder seasons and decorate more sheltered areas throughout much of the year.

Fauna

Desert fauna of the site includes a variety of specialized invertebrates.  Because of the remoteness of the area, very little invertebrate collecting has been done.  A preliminary survey of the ground-dwelling spiders, using pitfall traps have yielded 66 species distributed in 46 genera and 24 families.  Several species are new to science and one may well be a new family to science (Broussard and Horner 2006, Platnick and Horner 2007).  Identified solifugids include six different species from five genera and two families.

Vertebrates are the typical Chihuahuan Desert animals such as the cactus mouse (Peromyscus eremicus), desert cottontail (Sylvilagus audubonii), black-tailed Jackrabbit (Lepus californicus) , javelina or collared peccary (Taxidea taxus)  mule deer (Odocoileus hemionus), kit fox (Vulpes macrotis), coyote (Canis latrans), mountain lion (Puma concolor), etc.  Approximately 90 species of birds, mostly migrants, have been identified at DDRS by a current study (Holbert in prep).  Numerous bats, lizards, snakes, and insects are present, but are yet to be identified.

The geological features of the DDRS are highly varied and the topography is complex.  The uplands in the western part of the site consist primarily of desert pediments overlying the Oligocene Tascotal Mesa Formation and the Mitchell Mesa Welded Tuff, which is dated at about 32 mya.  Both units are the product of volcanic activity in the Chinati Mountains far to the west.  The eastern part of the site includes an extensive exposure of the Eocene to early Oligocene Devil’s Graveyard Formation, which is approximately 235 m (750 ft) thick below a north-south trending escarpment.  These layered fluvial and lacustrine volcaniclastic sediments are now being eroded into badlands-type topography by water and wind. Two forks of Alamo de Cesario Creek cut through the property and have created typical desert arroyos, buttes, mesas, alluvial fans, and hoodoos.  The southern part of the DDRS is transected by a major east-west trending faultline, the Tascotal Mesa Fault.  South and west of this fault are outcrops of the Rawls Basalt, produced 28 mya by volcanic activity in the Bofecillos Mountains.

The DDRS provides many opportunities for learning and research in the Geosciences. Though there are a several publications dealing with the geology of the area, comprehensive mapping and description of the rock units on the property have yet to be undertaken. Mapping can be accomplished through a combination of remote sensing and field mapping techniques, enabling units on the property to be correlated to those found nearby. Description of the different rock types through petrographic and quantitative elemental analysis will further enhance understanding of the processes that shaped the geology of the area. With its highly variable and unique setting, the DDRS is an ideal outdoor laboratory for geosciences as well as environmental science majors. Field trips to the property have been and will continue to be conducted in conjunction with courses and research projects. In addition, the varied geology of the DDRS makes the site ideal for hosting a Geology Field Camp, which would involve students from MSU and other universities. Field camp, a six credit-hour course covering 6-8 weeks of practical field experience, is required for most geology majors across the country.