This is an Earthcache, which does not have a physical container, but provides a learning exercise and a chance to show that knowledge in this setting. Please send me the answers to the questions below to validate your log.
Background
SE Texas owes a lot to erosion, and avoiding the damages from erosion. Let's learn about the basics first.
Underneath your feet is what geologists generally call Alluvium. Specifically, the USGS (United States Geological Survey) classifies this portion as part of the Lissie Formation.
This formation is the basis of much of the lesson here, with it containing the reasons to fight erosion so carefully. Let's learn a little more about it.
The top portion contains clay, silt, sand, and very minor siliceous gravel of granule and small pebble size, gravel more abundant northwestward, locally calcareous, concretions of calcium carbonate, iron oxide, and iron-manganese oxides common in zone of weathering; fluviatile. The surface is fairly flat and featureless except for numerous rounded shallow depressions and pimple mounds, which leads to the ease of erosion. Total thickness is about 200 feet, so it sits for a good depth. It's age if from the Pleistocene era, which is the geological epoch that lasted from 2.58 million to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. This is one reason that it sits atop our whole area here, driving many charachtertistics.
What is Alluvium?
Alluvium is a general term for clay, silt, sand, gravel or similar unconsolidated detrital material, deposited during comparatively recent geologic time by a stream or other body of running water, as a sorted or semi sorted sediment.
Any running water moves the material along the path and deposits it elsewhere. Massive erosion, caused by heavy flow, takes its toll on the area, changing the characteristics. Changes in elevation along the stream add to the velocity of the water. Most of the water flowing in this area comes from rainfall, which can be heavy at times.
This area is different from common areas, as there is a large enough change in elevation to cause worry. This is coupled with the sediment make-up.
The Solution
To avoid the impacts of erosion, especially where a change in elevation is present, like this location, there are many ways to combat this. One example is shown here with a series of spillways. The spillways, made of material that does not erode, slow down and pool up the water, allowing it to the move at a slower pace down the stream, thereby limiting the erosion. These spillways are not common in Texas, as there generally is not enough elevation for them to work. Chaining several together combines the effect.
Logging Requirements
Go to the stated coordinates. Observe the spillways and the function, and answer the following questions, without posting answers in the log.
1. Can you see different mixes in the alluvium, as described above? How do they play into the erosion?
2. Can you tell why this portion was chosen for the spillways?
3. Are the spillways defeating erosion?
You may log the cache after sending answers. I will notify if there is a problem. Pictures are encouraged, but not required.