Weather or Not to do an Earth Cache EarthCache
Weather or Not to do an Earth Cache
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A short round trip walk of less than a mile to view some unique weathering examples.
Remember there is no container here to find. To get credit you must answer the questions and upload a photo with your log.
Everywhere around us weathering is occurring to the surface of the Earth; changing what we see around us. Weathering is defined as the breakdown and disintegration of rock into smaller pieces of sediment and dissolved materials. Though similar in end effect, weathering should not be confused with erosion which requires movement of forces to occur. These forces are things like water or wind. Weathering includes no movement to occur.
Through tectonic or man-made activities rocks become exposed to the surface. When they reach the surface they interact with forces and begin to weather. Once exposed several factors play in how the rock is affected by weathering.
MINERAL COMPOSITION –Some minerals by their composition alone are more susceptible to weathering.
JOINTING –Joints are lines of weakness in rocks. Roots of trees and rain water can enter the joints and bring about physical and chemical weathering.
GRAIN SIZE –The bigger the grains, the faster it will be weathered.
RELIEF –When the relief of a place is steep, landslides and slumping may occur, exposing the underlying rocks to weathering especially physical.
CLIMATE –The rate of chemical weathering increases as temperature and rainfall increase. When there is a large diurnal range of temperature, exfoliation, granular disintegration and block disintegration are active. When temperature fluctuate around freezing point (e.g. in mountain areas)
VEGETATION COVER –Vegetation retains rain water and thus the rocks are subjected to chemical weathering. The roots of plants also open up cracks, expose more rocks to weathering.
MAN'S ACTIVITIES –Man's industrial activities cause pollution (sulphur dioxide) in the air. When rain mixes with the gases, it forms acid rain which breaks down rocks rapidly.
TIME –All weathering is determined by time. How long a rock has been exposed determines the effect of weathering.
There are two main types of weathering: Mechanical or Chemical. Physical Weathering is physical disintegration of a rock into smaller fragments, each with the same properties as the original. Occurs mainly by temperature and pressure changes and occurs most easily in places with large temperature changes. Chemical weathering involves the change in the make-up of the rock it is affecting. These changes in the rock then lead to the breaking down of the form of the rock. Acid rain and other pollutants are good examples of chemical weathering
All around in Gifford Pinchot State Park you will find examples of a specific type of weathering called Spheroidal Weathering. The rocks throughout the park are Triassac diabase that is dark-gray, massive, dense and uniformly fine-grained. These rocks while cooling from magma formed circular patterns of joints from the shrinkage caused as they cooled. Exposed outcroppings weathered into these rounded boulders. Think of the circular joints like an onion that was slowly pulled away along with the outside sharper more angular features of the rock.
To gain credit for this earth cache, please do the following:
1. Describe the unique rock formation that you are viewing?
2. Explain how you feel this feature was formed, beyond just the spheroidal weathering that has taken place here?
3. What’s the most common rock found in the park? What’s the least common rock type found in the park? (No guessing here there’s a document that will help you with your answer and further your education or check with a ranger)
4. Take a photo of yourself with your GPSr in hand in front of some of the spheroidal weathered stones in the area and post it with your log.
There have been a few logs that have mentioned some kind of letterbox. Whatever that is it has nothing to do with my earth cache. Please answer all of the questions to me in an email before posting a "found" log. Logs without the answers or photo will be deleted.
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