Belton Lake is a U.S. Army Corps of Engineers reservoir on the Leon River, 5 miles (8 km) northwest of Belton, Texas. Belton Dam and the lake are both managed by the U.S. Army Corps of Engineers. The reservoir was officially impounded in 1954, and serves to provide both flood control and drinking water for Belton, Temple, and the surrounding communities.
Belton Lake overflowed the spillway in 1991 and 1992 with the occurrence of two closely spaced 50-year floods. The area immediately below the spillway was heavily damaged. That area was rebuilt and reconstituted as the Miller Springs Nature Center in October 1993 with nearly 11 miles of hiking and biking trails.
The Edwards Plateau is an uplifted and elevated region of central Texas primarily of limestone. It was originally formed from marine deposits of sandstone, limestone, shales, and dolomites during the Cretaceous Period, 100 million years ago, when this region was covered by an ocean.
The limestones of the Edwards formation form the cap rock on the divides between the principal drainage ways and on the numerous buttes. The topography of the section within and adjacent to the lower portion of the reservoir, where the Edwards limestones are more prevalent, is moderately rough. The Edwards usually forms steep bluffs along the principal streams and the smaller creeks and drains.
Chert is a microcrystalline sedimentary rock composed of silicon dioxide (SiO2). It occurs as nodules, concretionary masses, and as layered deposits. As chert nodules or concretions grow within a sediment mass, their growth can incorporate significant amounts of the surrounding sediment as inclusions. These inclusions then impart a distinctive color to the chert. The darker colors result from inclusions of sediment or organic matter. Reddish brown chert receives its color from included iron oxide.
Chert breaks with a conchoidal (curved clam shell like) fracture producing very sharp edges. Early people took advantage of how chert breaks and used it to fashion cutting tools and weapons. The name "flint" is also often used for this material. The sharp edges of broken chert tend to retain their sharpness because chert is a very hard and very durable.
Chert is not found everywhere; but where it is found, early people used it to make knives, arrow and spear points, scrappers, and axes. Pieces of chert and nodules were also used as valuable trade goods.
To log this Earthcache, go to the posted coordinates, and stop on the ramp to observe the cliff face to your left. Then proceed on down the ramp to observe the whole face in this local.
From the description information and your observations at the GZ answer the following questions. Message or email the correct answers to get credit for this earth cache. “Finds” without supporting correct answers will be deleted.
- In your own words what is chert and why was it useful?
- At this location is the chert in the form of nodules or a continuous deposit?
- What color is this chert and any inclusions?
- Approximately how high is the cliff?
- Go on down the ramp to the ground and stand where you can see along the cliff face on both sides of the ramp. Observing the strata of the cliff from left to right. Is it straight, up thrust, or down thrust?