MI - Alger Falls Weathered Protrusions EC EarthCache
MI - Alger Falls Weathered Protrusions EC
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As an Earthcache, there is no container to discover. Rather, with this cache, you discover something interesting about the geology of the area. To receive credit for this 'find' please e-mail to my profile the answers to the following questions.
Logging Requirements: 1- Determine whether the 'weathering' that you are seeing is PRIMARILY mechanical or chemical weathering. 2- List the TYPES of mechanical and chemical weathering that you observe. 3- Submit a pic and/or submit an estimated height and width of the complete falls. This is a roadside EarthCache. * * * * * * * * * * * * * * * Alger Falls is one of 134 waterfalls in Michigan, all but one of which is in the Upper Penninsula.This earthcache is NOT about the 'falls', there are already several EarthCaches that explain their geology, but it is about the 'weathering' process of the rocks at the edges of this waterfall. This earthcache relates to the rocks along the edges of the falls as well as along the stream at the base of the falls. Choose a location at either edge of the falls or at the edges of the stream at the base of the falls. You are trying to determine the REASONS for the 'weathering' that is taking place on these rock formations. Geology: The Upper Penisula of Michigan is a unique place geologically because it is at the "border" of where the Candian Shield, the Wiconsian shield, and other "rock shaping" events took place. That is one of the reasons there are so many waterfalls -- there are several different kinds of rocks present, with several different HARDNESSES, and so of course, weathering will affect the rock in different ways based on its ability to "cut through" the rock as water rushes from one point to another (and there is enough snow, rain, and other "weather" up here to write a book about!). Notice the layers and layers of sedimentary rock.This is a stair step falls. Weathering is the decomposition of the earth's rocks, soils and minerals through direct contact with the atmosphere. Weathering occurs without movement, meaning that erosion is NOT considered to be weathering, though it may have caused the environment for weathering. There are TWO TYPES of weatheriing - MECHANICAL (PHYSICAL) and CHEMICAL. MECHANICAL WEATHERING - involves the breakdown of the rocks and soils through their direct contact with atmospheric conditions such as water, ice and preasure. Mechanical weathering is a major cause of the disintergration of rocks. The rock size is brokendown into smaller particles but the rock components are NOT altered. CHEMICAL WEATHERING - involves the direct affect of atmospheric chemicals or biologically produced chemicals in the breakdown of the rocks, soils and minerals. The composition of the rock components DOES change in chemical weathering. The minerals left over after the rocks breakdown combined with organic material creates soil. The mineral content of soil is determined by its parent soil sources. Thus, a soil derived from a single rock type can often be deficient in one or more minerals for good fertility, while a soil weathered from a mix of rock types often makes a more fertile soil. TYPES OF MECHANICAL WEATHERING: THERMAL EXPANSION - This type of mechanical weathering happen when there is a great CHANGE in temperature on a clyclic basis. The stress of the temperature change causes the peeling off of the layers of rock into sheets. Thermal expansion is increased by moisture. FROST DISINTERGRATION - This happens in environments with alot of moisture and where the temperature often fluctuates above and below freezing. When the water freezes it crystalizes and expands, producing stress on the rock. Sandstone and limestone are especially vulnerable to this type of weathering. BIOLOGICAL WEATHERING - Living organisms may contribute to mechanical as well as chemical weathering. The attachment of organisms to the rock surface enhances physical as well as chemical breakdown of the surface microlayers. On a larger scale, seedlings sprouting in a crevive and plant roots exert preasure as well as providing for water and chemical infilteration. TYPES OF CHEMICAL WEATHERING DISSILUTION - Rainfall is acidic because atmospheric carbon dioxide dissolves in the rainwater producing weak carbonic acid. It is the cause of acid rain, and the acidicness is 2-3X normal. CARBONATION - This takes place when rain combines with carbon dioxide. It has an effect especially on sandstone and limestone because the weak carbonic acid formed reacts with calcium carbonate. BIOLOGICAL - CHEMICAL WEATHERIING - A number of plants and animals may contribute biological/chemical weathering. The decaying remains of plants and the waste of animals from organic acids which when dissolved in water causes chemical weathering. Hydrology: Algers Creek is part of the Manistique Watershed that covers the majorty of the land in the central eastern part of the U.P. from Lake Superior to Lake Michigan/Huron. There are no major rivers in this watershed but rather a series of creeks and hills that channel the water dispersantly to the Lakes. For a watershed map of Michigan visit: http://bit.ly/MIwater Resources: msstate.edu Geoscience department online "Alger Falls" gowaterfalling.com Epa.gov -- http://bit.ly/Algers1 (you can find ANY watershed in the entire USA here along with pertinent earth science, geological, and hydrological information available for that watershed) Great USA weather/temp map http://bit.ly/Algers2
Additional Hints
(Decrypt)
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