Grand Valley Erratics
Geologists define erratics as stones or boulders that have been carried from their place of origin by a glacier and then left stranded by melting ice on bedrock of a different composition.
Most glacial erratics appear worn and rounded, and sometimes include beveled or faceted surfaces. During the course of their journey, the rocks were jostled against other erratics or scraped against the underlying bedrock, rounding off corners and planing smooth surfaces, eventually producing their characteristic appearance. Glacial transport also caused some boulders to fracture, producing fresh angular edges. Rocks carried by rivers also undergo abrasion and become rounded in the process.
Two major rock types are found in Michigan. The Lower Peninsula and the eastern parts of the Upper Peninsula are underlaid by a series of sedimentary rock layers. These rock formations consist largely of shales, limestones, and sandstones. The various layers of sedimentary rock are piled up on top of one another like a series of saucers. Igneous and metamorphic rocks compose the western part of the Upper Peninsula make up the second category of rocks. Igneous rocks are hard, crystalline, resistant to erosion, and are largely made up of granites and metamorphic rocks — rocks that have been changed through heat and pressure — composed mainly of gneisses and schists. Both major types of rocks found in Michigan are important to humans. The igneous type contains valuable minerals such as iron ore and copper, and the sedimentary rocks contain petroleum, natural gas, salt, gypsum, and limestone.
Allendale was in a very strategic area for early commerce along the Grand River, which borders the township to the North. This was an indication of its future development. After the depletion of fur trading came lumbering and mill work. Allendale pine forests consisting of maple, elm, beech, and white oak were lumbered off and shipped by river to Grand Rapids. No timber was shipped until it was sawed into lumber and, thus, saw mills became prevalent. A large one still in operation as late as 1896 was located in the village of Allendale on 68th Street..
Transportation by water was most convenient and economical. Ferries and bridges were built to provide river crossings for wagons and trucks to reach markets in Grand Rapids. In 1917, the Eastmanville Bridge was completed, the only river-crossing access in central Ottawa County. The soils and topographic conditions in Allendale are generally suitable for most types of urbandevelopment. The Grand River also is an important natural resource impacting the residential growth in the area. Allendale is named for the township. malta was intially chosen as the name for the township, however when the township was organized in 1849, state senator Pennoyer changed the name to Allendale, after Agnes Allen, the first person on the tax roll in the area and the widow of Hannibal Allen, who was the son of Revolutionary War hero Ethan Allen.
To receive credit for this Earthcache find:
1. Take a picture of the erratic – do not take this picture from distance greater than 3 feet away. Do not post this with your log – you will use this for step #8
2. Determine the width of the erratic (when viewing the plaque this is the left to right distance). This will be considered the diameter. Divide this number in half to calculate the radius. Using this information to determine the volume of the erratic based on a spherical volume (Volume = 4/3 * 3.14159 * radius cubed). Your answer will result in a cubic foot measurement. Now determine the weight of the Erratic by taking your answer and multiplying by 150 lbs/cubic feet. You will get an answer is pounds.
3. Read the plaque and write down the name on it
4. Go to N 42° 58.141 W 085° 57.138 and take a picture of the erratic – do not take this picture from distance greater than 3 feet away. Do not post this with your log – you will use this for setp #8.
5. Determine the height of the erratic and divide that value in half. This will be considered this "a". Determine the width of the erratic (this is done by measuring the left to right distance when facing the plaques) and divide that value in half. This will be considered "b". Determine the depth of the erratic (this is done by measuring the front to back distance of the erratic when facing the plaques) and divide that value in half. This will be considered "c". Using the values of "a", "b", and "c", determine the volume of this erratic based on a Ellipsoid volume (Volume = 4/3 * 3.14159 * a*b*c). Your answer will result in a cubic foot measurement. Now determine the weight of this Erratic by taking your answer and multiplying by 150 lbs/cubic feet. You will get an answer is pounds.
6. Read the plaques and write down the names on them
7. At this location, take a picture of you, with your face and GPSr visible with playground in the background. Post this photo with your online log
8. Using the following links and your photos of the erratics, determine the rock types of the erratics. (Note they are not the same)
9. Please send me an-email through my profile the answers to #2, #3, #5, #6, and #8 when logging your find. Please indicate the time of your visit in your online log
All required information and photo is to be provided within 24 hours of posting your "Found It" log. Be sure to include in your e-mail the time you were there.
ach person claiming a find on this earthcache is required to submit the required information ***
The purpose of an Earthcache is for everyone to learn from their visit/experience. Combined photos are acceptable, but each geocacher must be identified.
Failure to comply with the requirements for this Earthcache will result in a deletion of your find.
***= the only exception to this is young kids that are caching with their parents (who have their own account, but not computer privileges).
Congratulations to Tom_Kat on the First To Find of this Earthcache.