Llano Estacado - Geography and Climate

Geography and Climate

The Llano Estacado lies at the southern end of the High Plains section of the Great Plains of North America; it is part of what was once called the Great American Desert. The Canadian River forms the Llano's northern boundary, separating it from the rest of the High Plains. To the east, the Caprock Escarpment, a precipitous cliff about 300 feet (100 m) high, lies between the Llano and the red Permian plains of Texas; while to the west, the Mescalero Escarpment demarcates the edge of the Pecos River valley. The Llano has no natural southern boundary, instead blending into the Edwards Plateau near Big Spring, Texas. This geographic area stretches about 250 miles (400 km) north to south, and 150 miles (240 km) east to west, a total area of some 37,500 square miles (97,000 km2), larger than Indiana and 12 other states. It covers all or part of 33 Texas counties and four New Mexico counties.

Spanish conquistador Francisco Coronado, the first European to traverse this "sea of grass" in 1541, described it as follows: "I reached some plains so vast, that I did not find their limit anywhere I went, although I travelled over them for more than 300 leagues ... with no more land marks than if we had been swallowed up by the sea ... there was not a stone, nor bit of rising ground, nor a tree, nor a shrub, nor anything to go by."

After his 1852 expedition to explore the headwaters of the Red and Colorado Rivers, General Randolph Marcy agreed: " a tree, shrub, or any other herbage to intercept the vision... the almost total absence of water causes all animals to shun it: even the Indians do not venture to cross it except at two or three places." The landscape is, however, dotted by numerous small playa lakes, depressions that seasonally fill with water and provide important habitat for waterfowl. As the Spanish word estancado means "stagnant" (water), a growing number of geographers and geoscience researchers from Texas Tech University are considering that the region was originally named Llano Estancado for these lakes.

The Llano Estacado has a semiarid climate (Köppen Bsk), characterized by long, hot summers and cold winters. Rainfall is extremely low; the entire region receives fewer than 23 inches (580 mm) of rainfall annually, and the western part receives as little as 14 inches (360 mm). High summer temperatures (average July temperature above 85 °F/29 °C) mean that most of the small amount of precipitation is lost to evaporation, making dry-land farming extremely difficult.

• Caprock Escarpment south of Ralls, Texas

• The northern edge of the Llano Estacado in New Mexico

• Wind turbines on the windswept Llano Estacado