Most papers about the history of geology concern evolution of concepts or sequences of events. This paper turns that on its ear – it shows how geology can influence history.
The Edwards Plateau is an immense, high-standing tableland that covers more than 25,000 square miles of west-central Texas, the geomorphic expression of the thick, resistant Edwards Limestone. Rainfall tends to sink into the permeable limestone terranes on top of the plateau, rather than run off. Because the Trinity-age mudstone formations underlying the porous Edwards Limestone mass are relatively impervious, ground water accumulates in the lower part of the Edwards, forming an extensive regional aquifer up to 300 feet thick.
This ground water is the source of all the springs around the margins of the plateau.
The consequences of this geology are unusual: a vast, elevated, waterless plain, dissected around its serrated margins by deep, limestone-cliffed canyons, each fed by perennial springs that form the headwaters of all the rivers in central and south Texas, save the Pecos and the Rio Grande.
This singular geologic/geomorphic/hydrologic combination exerted a profound influence on settlement and development of the region during the late 19th century. All frontier settlements were proximal to perennial, spring-fed streams – but the Edwards Plateau itself, because of its rugged margins and the absence of dependable surface water, constituted a formidable wilderness barrier to permanent habitation.
Early road networks mostly went around the plateau, and the Western Beef Trail skirted its eastern margins. During the 1870s, marauding Indians raiding southeastward from the High Plains and northeastward from Coahuila utilized the flat, thick-turfed plateau uplands as wilderness pathways to fall suddenly upon unsuspecting settlements around the margins of the plateau, thus inhibiting permanent Anglo settlement.
In 1873, the U.S. Army began to suppress raiding into Texas by Comanche and Kiowa Indians from Indian Territory (now Oklahoma). Even though Kickapoo and Lipan Indians continued to raid from safe-havens in northern Mexico, opportunistic Anglo-Celtic cattlemen and homesteaders began settling the wide apron of open, stream-laced lands that bordered the Edwards Plateau on the east.
Family-based criminal confederations also were attracted to such isolated locations because of the sparse populations, lack of organized government and law, proximity to clandestine livestock markets along the Mexican border and the adjacent wilderness as a waiting refuge from pursuing lawmen.
Isolated by geology and by-passed by history, the canyon lands around the forks of the Llano River – in unorganized and lawless Kimble County – provided an ideal location for such a tribal confederation of frontier outlaws beginning in 1874.
They preyed on neighboring settlers, north-bound trail herds and stock raisers in adjacent counties, sometimes disguised as Indians.
Outnumbering and intimidating law-abiding settlers, they took over the Kimble County government shortly after it was organized in 1876.
They robbed stagecoaches repeatedly. They routinely drove stolen livestock across the Edwards Plateau to Mexican border markets, and returned with other livestock and goods to trade with northbound trail bosses.
They traded regularly in Mexican border markets alongside Mexican Indian raiders, and they might have participated with Mexican Indians in the brutal massacre of four young people of the Dowdy family in Kerr County in 1878.
Starting in 1876, sustained campaigns by the Frontier Battalion (Texas Rangers), aiding fearful settlers and beleaguered county lawmen, gradually brought order to the region.
The Rangers’ first campaign, the “Kimble County Cleanup” (April 1877), was an organized surprise sweep of the upper Llano River valleys by about 35 Rangers, who arrested more than 40 suspects and allowed the first district court to be held in Junction City. Outlaws who were county officials resigned.
The first grand jury indicted 25 suspects, but there were not enough honest citizens left over to form a 12-man jury, so the trials were continued until the next district court term. Many outlaws took the hint and left the area, but the criminal confederation organized around the Boyce, Dublin and Potter families stayed.
So did the Rangers – they maintained a permanent camp near Junction City for four more years.
Dick Dublin, leader of the confederation, was killed by Ranger Cpl. Jim Gillett in early 1878. The next summer, Ranger squads arrested six gang members suspected of repeatedly robbing stage coaches carrying military payrolls for Forts McKavett and Concho and jailed them in Austin, to be tried in federal court. One (Rube Boyce) made a spectacular escape from the Austin jail; the rest were convicted in August 1880, and sent to federal prison in Illinois.
In September 1880, outlaws of the Potter family stole a horse herd in Kimble County and headed west across the plateau, pursued by Cpl. Rush Kimbell and six other Rangers. Kimbell’s rangers caught up with two of the outlaws at Pope’s Crossing of the Pecos River, where they killed one and captured the other.
This marked the end of the Kimble County criminal confederation.
But late-19th century technology would end the influence of the Edwards Plateau on frontier settlement history. In 1882 railroads were completed that skirted the plateau on the north and south. This put an end to the cattle drives and regional stagecoach-lines.
The plateau uplands began to be settled in the mid-1880s, when the widespread use of cable-tool drilling and windmills began to provide reliable water sources for livestock and permanent habitations, and barbed wire allowed ranchers to control grazing.
The frontier era was over in the region of the western Hill Country of Texas and Edwards Plateau.
But geology continues its influence today: the Edwards Plateau remains sparsely populated.
Migrants from Mexico still cross its semi-arid expanses furtively, and the only changes since 1880 are windmills, barbed wire fences, a few paved highways, widely scattered small towns, well-heads producing oil and gas from the prolific Permian Basin underneath the plateau and the caliche roads that service them.
This summary is fully developed as a documented history in “The Reckoning: The Triumph of Order on the Texas Outlaw Frontier,” by Peter R. Rose, released by Texas Tech University Press in September. Rose, is a past president of AAPG.
Historical Highlights is an ongoing EXPLORER series that celebrates the "eureka" moments of petroleum geology, the rise of key concepts, the discoveries that made a difference, the perseverance and ingenuity of our colleagues – and/or their luck! – through stories that emphasize the anecdotes, the good yarns and the human interest side of our E&P profession. If you have such a story – and who doesn't? – and you'd like to share it with your fellow AAPG members, contact Hans Krause.