Monitor Mine EarthCache
Hidden : 7/21/2012
Difficulty:
1 out of 5
Terrain:
1 out of 5

Size: Size: other (other)

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Geocache Description:

**Please note that Earth Caches require you answer questions, which are at the end of the page. Failure to send these answers within a week of logging the cache will result in deletion of your log.**

We’re not anywhere near any mountains or have any other indication that minerals lie below the surface of the Saginaw Bay region. Did you know that this area is full of coal?


Coal is formed when plants in swamps die. They sink below the water, but swamps are low in oxygen, which prevents a lot of decay. The dead plant matter builds up. Eventually there has to be a layer of some sort of sediment over the plants, which compresses the plant material into a sedimentary rock.
Plant debris accumulates slowly. During the time it is building up, the water level of the swamp must remain stable. If it gets too deep, the plants in the swamp will drown. If the water cover gets too low, the plant matter will decay. Because of this, coal formation is rather unusual. It only happens under two conditions: 1) rising water keeps the same pace as debris accumulation or 2) a subsiding landscape  keeps pace with the accumulation of plant debris. Most coal forms in a delta environment (#2). (source: http://geology.com/rocks/coal.shtml)

So, why would there be coal here?

Long ago, Michigan used to be covered by a shallow sea. This is responsible for the limestone and sandstone in the area. Crustal movement cut off this area of water from the rest, forming a swampy area. I found a website that drew a beautiful picture of what this area was like:

“Sedimentation was partly marine, partly fresh or brackish water in swamps. A layer of sparkling sand was first spread over the last Mississippian limestone and above this in the shallow waters a luxuriant swamp forest flourished --- but the trees were quite unlike our modern trees. They were giant fern trees, ground pines, and horsetail rushes that grew to 10 meters or more in height. No birds or butterflies or flowers were there, but dark loathsome amphibians and the earliest known reptiles crawled in the muds; giant scorpions and dragonflies flew about. The climate was warm and moist. The swamp vegetation died and fell to the swamp floor, layer upon layer of plant remains accumulated, changed to peat, were buried under a blanket of dark muds which slow streams brought from forest covered lands. Thus protected from oxygen, they have become the coal beds and shales of the central counties.” (source:  http://www.geo.msu.edu/geogmich/coal.html)

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(source:  http://www.geo.msu.edu/geogmich/coal.html)
Michigan’s coal is low quality and shows up in thin seams, which makes it unworthy of mining compared to other areas that can produce better and more coal. This didn’t stop many from opening mines in the area.

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Source: http://www.michigan.gov/documents/deq/GIMDL-CMBAYA_301932_7.PDF

The slag pile you can see at the posted coordinates is left over from the Monitor Mine, one of many around this area.
 
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http://www.mybaycity.com/scripts/p3_v2/P3V2-0200.cfm?P3_NewspaperID=888&P3_articleID=4623

The coordinates above are for the closest viewing area of the remaining slag pile. It is just off of the corner of Bay Road (84) and Hotchkiss.

To log this earthcache you must send me answers to the following questions through a message. Do NOT post these in your log or it will be deleted.
1. Which of the two ways, based on the description above, do you think the local coal was formed?
2. The color of the slag pile used to be visible, but has been covered over with sod. How high is the pile?

If you'd like, you can post a picture of yourself with the slag pile in the background.

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