While exploring downtown San Antonio, I came across the historic Bexar County Courthouse which incorporates the local geology into its own construction. Here, according to the Texas State Historical Marker, the building was built using Native Texas Granite and Red Sandstone at a cost of $621,000 in 1890. James Riely Gordon was the architect who designed the courthouse.
At the above coordinates, you will see the front of the courthouse which is prominent in red sandstone, a type of sedimentary rock. A sedimentary rock is made of smaller fragments from other types of rocks (could be other sedimentary rocks, or it could be igneous or metamorphic). In this case, sand grains make up the rock. There are two types of sandstone deposits. A marine sandstone deposit was formed close to the shore (or part of the shore like a beach). These often contain shell and other marine fossils. A terrestrial sandstone deposit formed from a large desert sand dunes. Some examples include the large sandstone deposits of Arizona and Utah. These contain no marine fossils and are much thicker in size.
The sandstone was buried under more and more sediment where it was compressed and heated to fuse the sand grains together. These specific sandstones formed in the Early Permian around 300 - 275 million years ago and today are found in North central Texas and south central Oklahoma. Fossils have been found and identified within these stones, so it is possible you may also find some!
Works Cited
https://www.unearthedstore.com/products/fossil-pecten-shells-france
https://www.stonecontact.com/products-305289/texas-red-sandstone-sonoma-cut-chopped
TO LOG A FIND ON THIS CACHE YOU MUST ANSWER ALL THE QUESTIONS BELOW. YOU CAN CONTACT ME THROUGH MY EMAIL OR THE GEOCACHING MESSAGE CENTER TO SEND YOUR ANSWERS. ANY INCORRECT ANSWERS MAY RESULT IN A CLARIFICATION RESPONSE FROM ME.
1. "Bexar County Courthouse" on the first line of your email AND list all geocaching names of your party so I can match your answers to them. If you all want to learn something, I would prefer each cacher send me individual emails in the spirt of earthcaching.
2. Take a photo of you (or your signature item if you don't want to show your face) with the courthouse in the background. This photo MUST be uploaded to your "found it" log. Please do not send any photos through the message center as Groundspeak compresses images. Each log MUST have a unique and different photo. No two logs may contain the same photo.
3. Describe the (a) range of colors, (b) textures, (c) and grain sizes of the sandstone.
4. Do you see any fossils? If so, describe them. If not, describe why this might be the case.
5. What are some clues that this sandstone formed on land (aeolian) rather than with water involved (beach or fluival)?