An
erRATic
in Jenison
Background
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
Local
History
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.
Logging
Requirements
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.