Geologic Highway Map of Texas
The earliest explorer that left some form of documentation of the geology of Texas was Baron von Humboldt around 1800. He was working for Spain and his most important quest was mineral wealth. A few years later, Philip Nolan and then William Kennedy published brief descriptions of the geology and topography of what was then the Republic of Texas.
Ferdinand Roemer was the first person to more fully document findings of the central part of Texas on the geology, botany and zoology of the new State of Texas. For this, he is known as the Father of Texas Geology. All of his work grew out of the movement of Germans to Texas spearheaded by Prince Carl Solms-Braunfels.
After 1850, the explorations of the geology of the area were based on military interests. Marcy explored and mapped the area to the north along the Red River and Emory surveyed the area along the Rio Grande. Emory Peak in the Big Bend National Park is named after him. It wasn’t until the 1880s that the State and the U.S. Government became more involved with geology and conducted the first surveys by the U.S. Geological Survey. These state and national surveys now provide the basis for all study of geology in the area.
Roemer’s work was especially interesting because it was original exploration that left documentation.
Prince Solms the first Commissioner-General of the Mainzer Verein wrote to the Berlin Academy of Sciences asking for help in finding an accomplished young geologist. The Academy chose Roemer who graduated with his doctorate in 1842 and began to seek physical proof of what he had learned by studying the mountains, river systems, lakes, fossils and mineral deposits in Germany.
Unfortunately all sorts of mismanagement plagued the new Verein consisting of noblemen whose name for their enterprise was: A Society for the Protection of German Immigrants in Texas. This is outlined in Roemer’s book, Roemer’s Texas 1845-1847 . The poor start with a land fraud boondoggle caused financial problems and lead Solms to engineer Baron von Meuesebach‘s move to Commissioner-General after he retired. According to Roemer, the situation turned out better than expected as New Braunfels ended up in a better situation than had been planned and Meuesebach proved to be a much better businessman.
Roemer arrived via Galveston late in 1845 and worked in Texas for 18 months as a geologist. He also did excellent work in other fields of natural history as you will remember from his botanical trips taken with Lindheimer out of New Braunfels. Roemer’s two important books published after he returned to Germany in 1849 and 1852 were “Texas” and Die Kriedebildungen that outlined the boundaries, topography, mineral products, botany, zoology, and literature of Texas; described the stratigraphy of time and rock units in southwest Texas, Central Texas and the Lower Gulf Coast.[1]
Roemer’s Texas obviously originated as a journal written by the 28 year old enthusiastic young man, relishing his job in Texas, doing work he loved. He met important ranchers, farmers, new colonizers, Indian traders and many Indian tribes. His descriptions include the people, their homes, businesses and the Indians clothing and their characteristics plus their trade items and what they traded them for.
Many times he compared things here with those he was familiar with in Germany. Such as the trumpet vines he found in the river bottoms “which is also cultivated at home as an ornamental plant”. He was delighted to see mountains, rivers and fossils existing in the same strata he had seen in Germany.
The preparation for the trips was simple: a sack of coffee, salt and zwieback went into the saddlebag. A tin vessel was tied to the back of the saddle and a rifle was carried for game or problems encountered. He had purchased a mule earlier on who he describes as “…a useful and trusty servant….who patiently allowed himself to be loaded with the manifold objects of natural history”. He said the animal’s appearance was often grotesque when returning from a collecting trip as in addition to himself the mule was burdened with a saddle bag of stones, a bundle of plants, perhaps a young alligator hanging behind the saddle and a four or five foot chicken snake suspended from the pommel.
Now let’s fast forward 146 years to October 23, 1993 when I joined some of my fellow geology students on THE LLANO FIELD TRIP, The Evolution of Central Texas, led by our instructor Thomas Hobbs of the Geology Department of North Harris College.[2]
McKinney Falls State Park. Basaltic lava flow from the Cretaceous volcano, Pilot Knob.
Reef beach rock formed when volcanic activity ceased at Pilot Knob. McKinney Falls.
Karst: Topography characterized by sinkholes, caves and underground drainage. McKinney Falls.
Enchanted Rock, elevation 1,825 feet, with a 360 degree panoramic view. The dome is part of a gigantic granite batholith that rose through the Packsaddle schist like a giant hot balloon about a billion years ago. It is now exfoliating (peeling away in thin layers).
Willow Creek metamorphosed ophiolites that were pinched off the subducting ocean crust during the Grenville Orogeny. The crustal basalts were altered to produce low grade serpentine, talc and graphite.
A breathtakingly beautiful example of Grenville Orogeny folding and metamorphism. Stewart Ranch.
Road cut example of faulting and formation of a graben sliding down between the rock strata on both sides.
Pink gneiss in granite. Inks Lake State Park. The pink gneiss originated from fine-grained rocks that formed large and small dikes and fissures in the granite under great heat and pressure that changed the two different rocks into metamorphic rocks.
Sauk sequence rocks at the Lake LBJ overlook. Note the layer with green glauconite with limestone clasts. A mineral of marine origin used in the textile, sugar, brewing and fertilizer industries. Its the layer just about ten feet over the roadway.
And now we jump 25 years to the present day when the earth’s movement continues to make it felt in our area.[4]
Note all the Balcones fault lines in Hays County. They are shown as disconnected red lihes. We are all familiar with the fault line that extends across Wonder World Dr. near the intersection of Old Ranch Rd. 12 as it is thrusting up again and the road is in need of repair. This fault extends to the Crestwood Strip mall on RR12 toward town where Faultline Liquor was once located.
Another fault in the vicinity is the one near the entrance to the Baptist Academy on RR12. This section of road was repaired recently, but will need repair again in the future because the ground keeps shifting.
Although we may envy those who live on the Blackland Prairie east of I 35 because they have a lot of real soil, we here in BWR in the limestone hills with a little of that black land prairie dirt makes for a salubrious situation. And dirt wise, it is better than the calcareous soil over Wimberley way.
Sightings
10-13-18. Two brightly colored male blue birds on the garden fence right back of the house. We observed them on two different days. We’ve seen and heard a few of the phoebes.
This is the first year we have experienced the Twig Girdler[5] bug. This very unusual bug cuts right around a tree branch that is about the size of a wooden pencil, completely severing the branch. The bug prefers certain trees, among which are pecan and cedar elm. Here is a photo of the bug just after it has nearly finished its work.
Books
R & D Tusch
[1] From The Geology of Texas Vol. 1, Sellards, Adkins and Plummer. Also see the colored map: the mostly green section and east to the lower coast.
[2] Now called Lone Star College.
[3] The clay can be used both externally and internally and is sold online by Target & Walmart. It usually forms from weathering ash most often in the presence of water. See: Pilot Knob in Roadside Geology of Texas.
[4] Map from Karst of the Urban Corridor by Kevin Stafford.
[5] www.ocws.okstate.edu
