Crystal Canyon Natural Area is a hidden oasis in Arlington, TX. This 40 acre park is part of a canyon for feeder streams associated with the Trinity River. The name is derived from the selenite crystals that can be found in different parts of the area. See the other Earthcache located in the park for more information on crystals.
While hiking through the park a group of us came across the nearby bridge and looked down at the unusual color of the water. Since there was a recent train wreck in East Palestine, OH that discharged chemicals into the local streams - we all immediately thought there must be some form of pollution to turn the water this blue color. However, one of our eagle eyed group quickly spotted a sign near GZ explaining that this was a natural phenomenan and not mad-made. I immediately decided that this needed an Earthcache!
The sign states that the water color is because of geochemical reaction between the groundwater and the mineral rich geology of the area. After a little more research here is what I found. In the late Campanian Stage of the Late Cretaceous age (80 Million Years Ago) This part of Texas was once covered in what is known as the Western Interior Seaway. This resulted in deposits that make up the geology of the Crystal Canyon including marine shales, siltstones, mudstones containing calcerous fossils, gypsum and fine grain sandstone. Over time the running water from the creeks have eroded away the material on the top creating the canyon. This erosion creates sediment in the water - probably Calcium Carbonate that ends up supsended in the water. The sun hits this suspended material and shines back giving the water a blue appearance.
To log this cache please answer the following questions using the geocaching app:
1) What color is the water in the creek under the bridge or in the nearby pools? Describe the color and the shade (e.g., Light Blue, Brown, etc.).
2) What color are the rocks on the bottom of the creek? What gives them this color?
3) In your own words why is the water in the creek this color?
4) What color do you think the water would be if the area has received recent rains?
5) Post a photo with you/your group and the water. (Optional)