Over the course of the past few months, I've found myself running this trail quite often. Something about the cool rock formations and cooling riverfront really distracts me from how bad my legs hurt. I've always wanted to put a cache down here to let others enjoy the area too. So, I invite you to visit the Brewer Hill Trail located in the West Virginia Core Arboretum.
The Brewer Hill Trail is a short trail, but I anticipate you will find it much different than the other trails in the area. While it does lead up the hill and presumably connects behind the W.V.U. athletic facilities, you should access this cache via the Mon River Trail. (Unless you want to try your hand at repelling; don't worry, the rope is provided.) Parking coordinates are listed in the waypoint list below.
Weathering
Weathering is the breakdown of rocks at the Earth’s surface, by the action of rainwater, extremes of temperature, and biological activity. Weathering is the process where rock is dissolved, worn away, or broken down into smaller and smaller pieces. There are mechanical, chemical, and organic weathering processes. Once the rock has been weakened and broken up by weathering it is ready for erosion. Erosion happens when rocks and sediments are picked up and moved to another place by ice, water, wind, or gravity.
Mechanical Weathering physically breaks up the rock. Mechanical, also known as physical weathering, can be divided into two main categories: fracturing and abrasion. Over time, pieces of rock can split off a rock face and big boulders are broken into smaller rocks and gravel.
Organic weathering happens when plants break up rocks with their growing roots or plant acids help dissolve rock. Organic or biological weathering can result from plant or animal activity. Such weathering can be quite subtle but can cause significant change over time. Tree roots, because of their size, cause a significant amount of biological weathering. But even much smaller plant-related actions can weather rocks.
Chemical weathering decomposes or decays rocks and minerals. An example of chemical weathering is water dissolving limestone. Water, and many chemical compounds found in water, is the main agent of chemical weathering. Feldspar, one of the most abundant rock-forming minerals, chemically reacts with water and water-soluble compounds to form clay. Water contains many weak acids such as carbonic acid. This weak, but abundant, acid is formed when carbon dioxide gas from the atmosphere mixes with rainwater. Sulfur dioxide and nitrogen gases create other types of acid rain that act as chemical weathering agents. Some sources of sulfur dioxide are power plants that burn coal, as well as volcanoes and coastal marshes. Sulfur gases react with oxygen and rainwater to form sulfuric acid. Although relatively weak, acid’s abundance and long-term effects produce noticeable damage to vegetation, fabrics, paints, and rocks.
Classifications of Depositions
All sedimentary rocks were deposited originally in rivers and streams on older land surfaces (terrestrial) or in oceans (marine) compressed by the weight of added deposits and generally cemented by quartz or calcite. Clastic sedimentary rocks contain particles and grains of older rocks, disintegrated by weathering and carried by wind or water to the site of deposition. Calcareous rocks have been cemented with calcite (calcium carbonate) and siliceous rock with quartz (silicon dioxide). Limestone contains mainly calcite, deposited as grains, nodules or fossils, or formed by chemical dissolution from water.
Particle sampling can be divided into two large components, namely particle size, using the Wentworth Scale, and particle shape, using the Powers’ Scale. Both are equally important in particle sampling.
Wentworth Scale is another name for the Udden-Wentworth scale, a grade scale for classifying the diameters of sediments. This system classifies particles from the largest boulders to the smallest particles found in clay (see chart below). Other scales are used, however the Wentworth scale is the one that is most frequently used in geology.
Powers' Scale of Roundness. This scale is defined by six roundness classes. Two sets of clay models were prepared to characterize each roundness class. One set shows a high sphericity, the other a low sphericity. Photographs of these models are used to determine the roundness of a particle by comparison (see chart below).
QUESTIONS!
To obtain credit for this earthcache, you will need to visit the rock formation on the Brewer Trail and answer questions about the area. The answers can be found by using the information on the cache page and your observations at the posted coordinates. Please send me a message with the two answers before logging this earthcache.
1. Using the Wentworth Scale above, classify the size of the sediment that has eroded off the rock?
2. Look at the sediment that has eroded off the rock again and identify its roundness using the Powers’ Scale.
OPTIONAL: Take a picture of yourself at ground zero and attach it with your log. Be sure not to reveal too much of the formation to avoid giving away the answers.