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Houston Stone Tour - Cedar Park Limestone

A cache by Texas Bandits Send Message to Owner Message this owner
Hidden : 02/19/2009
1 out of 5
1 out of 5

Size: Size: other (other)

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Geocache Description:

Houston, we have a Fossil!

Well, a fossil void.


After completing Shearzone’s "Calgary Building Stone Tour" Earth Cache series, I decided to look around downtown Houston to see if I could start up something similar. So, with all due credit to Shearzone, here goes!


Cedar Park Limestone , which is marketed as Cordova Shell, is a shelly, fossiliferous type of limestone which was formed approximately 100 million years ago in the Lower Cretaceous age. It is classified as a subdivion of the Walnut Formation in the Fredericksburg Group of the Upper Comanche Series.


Upper Comanche Series

Washita Group





Fredericksburg Group

Edwards Formation


Comanche Peak Formation


Walnut Formation

Keys Valley Marl

Whitestone Limestone

Cedar Park Limestone

Bee Cave Marl

Bull Creek Limestone


Cedar Park Limestone contains small fossils, crushed fossil debris and ooids. (Ooids are small, sedimentary "grains’ which are normally composed of calcium carbonate). Numerous fossil voids, or cavities, give the limestone its unique look.


Some of the fossils that created these voids are:

  • Trigonia – (From the Trigoniidae Family, aka Cordova Clams.) A highly ornamented bivalve which has a series of strong costae (ribs) along the frontal section of the shell’s exterior.




  • Turritella – (From the Turritellidae Family.) A medium-sized sea snail that has a tightly coiled shell and whose shape is that of an elongated cone.





  • Ceratostreon texanum - (From the Pycnodonteidae Family.) Another bivalve with a curved rib design and a small attachment scar on it’s lower valve.



Cedar Park Limestone is mainly quarried in the Texas Hill country and is usually found in approximately 40 foot thick sheets. It is commonly used as a dimension stone for constructing buildings. It has been used to help construct many government and private buildings throughout the United States, although the majority are in Texas. Some of the ones in the Houston area are the St. Thomas High School building, The San Jacinto Monument, and the Houston City Hall building. The latter is where you will complete this Earth Cache.



To claim this Earth Cache, you must complete the following steps:

(Email me the answers to steps 2 and 3)

  1. Take a picture of your GPS next to one of the fossil voids in the wall of the City Hall building. The coordinates are only a reference point so feel free to roam around the outside of the building to find a good spot for your picture.
  2. Using the images above if needed, identify the fossil void that is in your picture.
  3. Facing City Hall's main entrance, which is directly across from the reflection pond, you will see a bench to your right. Who is this bench dedicated to?

You will be able to gather all of the information you need from the walkways around City Hall. However, this is a public building, so feel free to explore it as well.

Congrats to crab and ram for being FTF!

Additional Hints (No hints available.)

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