An erRATic in Jenison
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
Rapid logging in this region soon depleted the supply of tree in the area and by the 1860’s the economic sustainability focus turned to farming. At the forefront of the new farming wave was the Jenison family along with other familiar Dutch Immigrants that made up most of the current area of Ottawa county at the time. Luman and Lucius Jenison established the L&L Jenison Mill in 1864. The mill was responsible for grinding harvested grain into flour. The contributions of the Jenison brothers and their family caused the town to be named after them.
This erratic is located in Jenison, MI near the Husban-Hanchett House at Port Sheldon and Main. You can see the house by looking to the immediate East. The Husban-Hanchett House was built in honor of Luman and Lucius Jenison. It now serves as the Jenison History Museum.
To receive credit for this earthcache find:
1. You must post a picture of you, with your face and GPSr visible with the erratic in the background.
2. Determine the height, width, and depth in units of FEET of the erratic.
3. Use this information to determine the volume of the erratic based on a spherical volume (Volume = 4/3 * 3.14159 * radius * radius *radius)
a. Calculate the volume of the erratic using the width or depth measurement (Remember to divide your measured value in half to determine the radius). Your answer will be in cubic feet.
b. Calculate the volume of the erratic using the height measurement (Remember to divide your measured value in half to determine the radius). Your answer will be in cubic feet
c. Determine the average volume of the erratic by adding "3a" and "3b" and dividing by 2.
4. Now based on the average volume you have calculated ("3c"), and a density of 150 lbs/cubic foot, determine the weight of the erratic
5. Please send me an-email through my profile the answers to #3 (a,b, and c) and #4 when logging your find. Please post your picture at the time of your log as well.
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.
Each person claiming a find on this earthcache is required to submit the required information*** (failure to comply will result in a deletion of your log).
The purpose of Earthcaches is for everyone to learn from their visit/experience. Combined photos are acceptable, but each cacher must be identified.
Failure to complete with the requirements for this earthcache will result in a deletion of your find.
*** = the only exception to this are young kids that are caching with their parents (who have their own account, but not computer privileges).
Congratulations to CacherX4 on the First To Find of this Earthcache.