Las Cruces, a rapidly growing city of 80,000 people, is located in south-central New Mexico, and is about 40 miles northwest of El Paso, TX and 30 miles north of the U.S./Mexico Border. The Organ Mountains flank the eastern part of the city, and the now tamed Rio Grande makes its way through the western portion. Elevation ranges from roughly 3,800' along the river, to approximately 4,200' along the east mesa.
The predominant life zone is typically Lower Sonoran, with mesquite, creosote, tarbush comprising the overstory, and grama grasses, and various species of yucca and cacti comprising the understory. Las Cruces is situated in the northern Chihuahuan Desert – the largest of the North American deserts – which is considered a "hot" desert. Winters can be cold, with average maximum and minimum temperatures reaching 57 degrees and 27 degrees Fahrenheit respectively. Summers are hot with daytime highs averaging 97 degrees, and lows averaging 65 degrees. Extremes can range from below zero (rare) to above 110 (more frequent). The area typically receives 8" of precipitation as rain, and 3" as snow annually. Average relative humidity is 25%; however summer levels can be as low as 8%.
Although desert conditions predominate, areas with considerably wetter, cooler and more diverse climates exist within an hour’s drive. The Gila National Forest is about 100 miles to the northwest and the Lincoln National Forest about 85 miles to the east. Both areas are high in elevation, with some locales reaching 12,000'. These forests support juniper, oak, spruce, pine, and aspen. Riparian areas also include dense forests of cottonwood.
The geology of the Las Cruces area is extraordinary and diverse. Included in the locally exposed ancient rock record is Precambrian basement, carbonate and siliciclastic Mesozoic and Paleozoic strata (which include El Capitan Reef and Carlsbad Caverns, locate in the Guadalupe Mountains), structures associated with the Laramide Orogeny and ancestral Rocky Mountains and Early Tertiary calderas and volcanics (which include the uplifted and exposed Organ Mountains, and Potrillo Mountains both in the vicinity of Las Cruces). There are also geologically modern sediments and landforms in the region. Crustal extension and subsequent faulting during the Late Tertiary, associated with the ancestral Rio Grande Rift, helped to create the modern basin and range topography of the region and intensified sediment deposition and erosion; the initiation of the Rio Grande about four million years ago also increased deposition and erosion in the area. The inceptions of these events have created fluvial deposits, alluvial deposits, modern soils (paleosols) that make pristine analogs for tectonic and sediment interaction. Another unique geological feature of the region is White Sands National Monument located in the Tularosa Basin northeast of Las Cruces. These gypsum dunes exist in a variety of forms and are continually changing due to the area’s prevailing southwesterly winds.