Geo-Joint: Roaming the Llano Estacado

Texas is a big state. It’s so doggone big that it has a broad variety of landscapes and geographic regions, and these regions themselves are sizeable. One of them is the Llano Estacado. It covers a vast amount of the western part of the state, from the Canadian River near Amarillo in the north down to the Midland/Odessa area in the south, and it runs halfway across the state to the east and well off into New Mexico on the west. Overall, it’s somewhere between 32,000 and 37,000 square miles depending upon how you define it, or about the size of Indiana. The Llano Estacado is the southern extension of the High Plains, which itself is the southern part of the Great Plains. It is bounded on the west by the Mescalero Escarpment above the Pecos River, and on the east by the 300-foot Caprock Escarpment, bold barriers in stark contrast to the wide tableland. The north is similarly incised by the southern escarpment of the Canadian River Valley. To the south, it slowly merges with the Edwards Plateau.

The Llano Estacado spills across the Texas/New Mexico border.

Plains are not known for their physical relief, and the Llano Estacado is exceptionally flat and featureless. It resulted from the massive sediments washed off not just the Rocky Mountains that we know today, but another previous range in the same location that wore away in the very distant past and laid itself down as a vast flat surface. Spanish explorer Francisco Vaquez de Coronado wandered across part of it, and in 1541 remarked that he found “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.” Legend has it that when Spanish explorers came looking for riches in the Southwest, the Native Americans told them, “Uh, yeah, there’s a big city of gold off to the east—just keep going, can’t miss it!” in hopes that the greedy foreigners would get themselves so far out there they’d get lost and perish for lack of water and supplies. Even those locals didn’t care to venture too far out onto the vast openness of the Llano Estacado. A story also got spun that in order not to get entirely disoriented, such exploration parties would pound stakes into the ground at intervals that they might follow to retrace their route. That “stake” business seemed to fit well with the name Coronado gave to the place, Llano Estacado, which was erroneously translated as the Staked Plain. However, what Coronado was noting as he christened the place were those huge escarpment walls that define the perimeter of much of the region, and the name he gave it actually translates to “palisaded plain,” or “stockaded plain,” a testament to these distinct topographical boundaries.

The lack of significant surface relief on the high plain of the Llano Estacado is clearly visible in this satellite image.

The Llano Estacado is largely a dead flat surface, but it’s on a tilt, raised up on its western side as part of the uplift that raised the Rockies. This uplift is what gave the Canadian and Pecos rivers to wear down into the plain and cut it off from surrounding regions. The plain slopes off to the east southeast at a rate of about 10 feet per mile, a difference that is hardly noticeable, although overall the elevation runs from a high of about 5,000 feet down to 3,000 feet at its southeastern end. The twenty or fewer inches of rain that do annually grace this arid region thus have a little bit of a downhill trend to follow, and they leave some small gullies (Coronado didn’t explore every inch of the place), but the Llano mainly drains internally, and small ponds that develop generally dry up in the hot sun. The soil ranges from sand to sandy loam and clay loam, and is productive when water is available. Without sufficient rainfall to support a wide range of crops, farmers in the area employ dry-land farming to raise such staples as sorghum and wheat. With irrigation technology, cotton, melons, and various vegetables became possible to produce on the plain. The irrigation water comes not from faraway rivers but is pumped from below ground, as the famous Ogallala Aquifer lies underfoot. As seems to be the story everywhere in the West and Southwest, the appetite for water supplies to make a garden in the near-desert far outstrips the recharging rate, and the aquifer is perennially overdrawn.

 

Looking down from the heights of the northwestern escarpment. The plain rolls out below.

The Caprock Escarpment on the eastern side. The caprock is a layer of sediment dense with mineral salts left behind when groundwater in it evaporated. It is hard and impermeable.

Most farming for crops on the Llano Estacado requires irrigation. Wind farming is a different story.

That water needed for crop irrigation and industry is tenuous. The lobe of the Ogallala Aquifer sitting below the Llano Estacado is poorly fed, and diminishing.

The biggest driver of the economy on the Llano Estacado grew up in the early part of the 20th century with the discovery of gas and oil. Those billions of barrels of oil brought industry, jobs, and prosperity to this formerly hardscrabble area. Like farming, however, the enterprise uses water, as do all the many people who are drawn to support the oil operations and a thousand other businesses. Amarillo, Lubbock, Midland, and Odessa have an uncertain future no matter the fate of the oil market, as the Ogallala Aquifer dwindles. Due to geologic peculiarities of the High Plains, that part of the aquifer under the Llano Estacado is cut off from the limited but more robust recharge that more northerly parts of the aquifer enjoy. Eventually, even that once massive store will no longer be able to feed the fields, cities, and industry that depend upon it so crucially. Sometime in the not-too-distant future, the Llano Estacado could once again resemble the barren, lonesome, and quiet scene that Coronado encountered.


Go see how flat the Llano Estacado is…and check out everything else Texas has to offer, guided by the Benchmark Texas Road and Recreation Atlas. It’s highly detailed, with gorgeous shaded relief mapping—and available from Maps.com.

CLICK HERE TO VIEW THE ATLAS!


PHOTO CREDITS:

caption: The lack of significant surface relief on the high plain of the Llano Estacado is clearly visible in this satellite image.
source: Wikimedia Commons: Unknown (Public domain)

caption: Looking down from the heights of the northwestern escarpment. The plain rolls out below.
source: Wikimedia Commons: Leaflet (CC by SA 3.0 Unported)

caption: The Caprock Escarpment on the eastern side. The caprock is a layer of sediment dense with mineral salts left behind when groundwater in it evaporated. It is hard and impermeable.
source: Wikimedia Commons: Leaflet (CC by SA 3.0)

caption: Most farming for crops on the Llano Estacado requires irrigation. Wind farming is a different story.
source: Wikimedia Commons: Leaflet (CC by SA 4.0 International)

caption: That water needed for crop irrigation and industry is tenuous. The lobe of the Ogallala Aquifer sitting below the Llano Estacado is poorly fed, and diminishing.
source: Wikimedia Commons: Kbh3rd (CC by SA 3.0 Unported)

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