Grand
Valley Erratics
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
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.
Logging
Requirements
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.