Gravel Pit Overview
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Sometimes the region I live in has the feeling of being a bit of a backwater. We're far removed from the metro and interstate action. So, just in case you have no idea what or where Michigan's NW LP is (Northwest Lower Peninsula), here's a view of the entire region:
Essentially, the whole place is a giant glaciated gravel pit.
Up in the northern 1/3rd of this "mitt" there are low ledges of bedrock exposed on the shores of Lake Michigan, as well on the Islands from South Fox on up, and there are several quarries operating in the area, but otherwise everything is covered in sand and rounded rocks. The formations in the northern 3rd are: the Gravel Point, Charlevoix, and Petosky Limestones; Norwood, Antrim, Jordan River Shales, and remnants of the Whiskey Creek Formation, all Devonian, in the Little Traverse Bay region. The Upper Silurian (Bass Island) crops out at the northern tip of the peninsula, and on the islands immediately to the west. Further north, on the Upper Peninsula, is the rest of the Silurian and the Ordovician.
After growing up in Missouri, where you can't walk a creek bed without finding fossils, Michigan seemed a bit of a fossil let-down. My folk's moved up here in the fall of 1985. We had been taking family vacations in the area for 10 years, escaping the July heat and humidity of St. Louis, MO., and my parents wanted a "change of lifestyle." Fortunately for me and my habitual rock hounding, they moved right next to an old and deep gravel pit.
Back then, seeing nothing but gravel and boulders, I didn't think there would be too much to interest me. Brachiopods were obvious, and there was plenty of glacialized coral, Petosky Stones (a Hexagonaria coral), favosites, and chain corals to be found, some of them interestingly preserved, and of course all the igneous rock you wanted -- pink and red granites stippled with green veins, jasper, agates, basalts, feldspar; more than I can identify. Stuff worth hunting for, but 2 or 3 walks a year was plenty.
As any seasoned fossil hunter knows, looks can be deceiving. After several years of being extremely busy and not really having the time to hunt properly, I finally do. Add to that the daily injections of inspiration I get from The Fossil Forum, and the 2 to 3 times per year walks have turned into 2 to 3 times per week.
The Goodies are coming in fast, and with a fair amount of surprising diversity.
It's amazing what you can find if you just spend the time to really look.
And, the more I look, the more questions I have regarding the original source of the fossils I'm finding, the influence and affect of the glaciers on the geology; the timing of their advance, how many advances there have been, their direction of movement, and the relative distances that they have moved rock, or when particular types of rock have been moved. How abundant is a type of rock in one area as compared to another across the North/South and East/West axis? Can "banding" of deposits be discerned to target particular types of fossils? Are any of the original sources for the fossil bearing boulders still present? If not, can one tentatively assign a rock to a formation/geologic era using fossils for correlation?
I intend to use this blog as a platform for exploring these questions and others that arise, what I learn, and as well as for sharing my finds.
Here's a map from Google Earth showing the pit closest to me, which I'll refer to as the Lincoln Rd. Pit; our greenhouses are in the upper left corner. You can see how short the walk is. Perfect for quick after work boulder smashing. The field to the west is our neighbor's. An ex-MSU extension agent. I think he plows it up just because he's bored, but the field is loaded with stone.
Wider view of the same area. Lincoln Rd. Pit is circled in yellow. To the west of the main pit, is a larger inactive pit, circled in black. Hunting there is a little sparser, but I'll hit it a few times a year. Greenhouses are circled in green. Due north of the greenhouses are two abandoned pits circled in black. One is on my dad's property, the other is private, but un-posted. The third, larger black circle to the north is the Benzie Co. Road Commission's gravel pit, dug into the north flank of Eden Hill, with no deep pit dug. Including the yearly plowed field, that's six spots to hunt in a 2 mile radius.
A view of the big ridge, Eden Hill, running NW - SE. Crystal Lake and the Betsie River Watershed is to the south, Platte Lakes & river watershed to the north. The big road that loops through the lower left is US31. Gravel pits/greenhouse in the center, circled in black.
And a full view of the general region, aka: Grand Traverse Region, named for the big double bay between the Leelanau and Old Mission Peninsulas. Leelanau Peninsula on the west. Sleeping Bear National Lakeshore runs from the middle of Benzie Co., north into the middle of Leelanau Co.
That's all for now.
Thanks for taking the time to check out my blog,
Tim
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