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Sunday, May 25, 2008

Rock and Roll

Been a long time
Been a long time
Been a long lonely, lonely, lonely, lonely, lonely
Time. . . .

- R. Plant

One of the nice things about taking a geology course at UWEC is that our class got to go on a field trip. This happy occasion occurred during the first weekend in May. It was an all-day affair and, in my opinion, ended up being a lot of fun. The day started out cool & wet, but, right about noon, the sun came out and warmed things up considerably. We went to a number of geologic sites in the Oak Lair (not its real name) area and got a good hands-on education involving the geologic history of western Wisconsin.

Our first stop was at the local landfill. Since the course's name was Environmental Geology, landfills and waste disposal were a part of the curriculum. Our bus actually drove around the site, and we got to view some interesting things involved in it's operation. One of these things is that of producing electricity from the methane gas produced by the breakdown of garbage products within the landfill area. The entire area was quite large, but the landfill takes in garbage from a large area and from as far away as Minnesota. We didn't get off the bus, but that was OK as it was cold and kind of raining while we were there.

Our next stop was at a very pleasant place that I'd been to before, a place called "Big Falls". This is a rather large whitewater area of the Oak Lair (not it's real name) River, in which the river has cut down through the local sandstone to the underlying (and much older) precambrian metamorphic rock. These rocks demonstrate a mountain-building event in Wisconsin, known as the Penokean Orogeny. They looked cool, and it was also nice for me to scope out a part of the river I plan on fishing later. (OK, OK, so I'm easily distracted that way. . . . ) We were also able to view, along the banks, the newer Mount Simon formation sandstone that I've blogged about before (because it underlies an awful lot of Wisconsin - it's more common than dirt here). All-in-all, this is a very cool place; I highly recommend it to anybody visiting the area.

After that, we proceeded to another river stop, this on the Chippewa River - a place called Jim's Falls. The geology there was similar but a bit more accessible. We ate lunch there and then did a bit of exploring. That's about the time that the sun came out and made for a pleasant day. One of the most notable things about the metamorphic rock in this area is how very deformed it is - often forming whorls and Z's - as shown in the photos below.

Next on the agenda was a gravel pit near Popple Lake. This was a stop that demonstrated what the glacial till of Wisconsin looks like. We all got to poke around in the sand and gravel for rocks, basically to see that there was quite a variety of rocks deposited there. The vast majority of these rocks were not from the local area, and many of them could be demonstrated to have been transported from far away to the north. These are the hallmarks of glacial deposition, and this whole area was known to have been at the glacial margin. On a side note - I did a naughty and I actually swiped a rock from this site. :) It's obviously part of a banded iron formation, and it looks cool too. Hey, now, it's not like it's going to be missed; and, besides, the officials that be can pry it from my cold, dead fingers. :)

The final destination of our trip was a place called Tilden. This was a sandstone/siltstone pit that was closer to Oak Lair. This is sandstone that is more recent than the Mount Simon formation; and, at Tilden, contained numerous cambrian-era fossils. We could also see, at the pit, that this sandstone/siltstone was laid down in a different fashion than the Mt. Simon stuff because there was no cross-bedding and the deposited material is much finer and smaller than that of the Mt. Simon formation. It was very easy to spot many fossils; however, I looked for, but didn't find, any trilobite fossils. Still, it was very cool to see evidence of critters that lived more than 300 million years ago!

Needless to be said, it was a very busy day. We saw a lot, did a lot, and, in my case, learned a lot. We got back to the university more tired than when we left, but I'm sure we all enjoyed it. I know that I did. Hopefully, all my geology field trips will be as fun and as cool as this one. Anyways, I figured I'd share all of this with you fellow blog-heads out there; so here are captioned photos for you to enjoy!

This is a photo, shot through the bus window, of the methane gas-powered electrical generator at the landfill.

This is a shot of "Big Falls". The river actually splits in half, this is the southern part. The other half is to the left of this view. The river is also very high with spring runoff.

Our group on one of the metamorphic outcroppings at "Big Falls".

Mount Simon formation sandstone (note crossbedding) along the banks of the river at "Big Falls".

Close-up of the metamorphic rock at "Big Falls", quarter for size-reference.

The view upriver from the Jim's Falls stop. The Chippewa River actually doesn't show actual flowage here, as there is a hydroelectric generation station just downriver; and part of the river's flow is diverted into that via a canal. Also, the bridge is blocked-off and derelict.

A good view of one of the granite inclusions that cross-cuts the metamorphic rocks at Jim's Falls.

This is a good view of how heavily-deformed the metamorphic rocks at the Jim's Falls location are.

One of my classmates (Aaron) obtaining rocks for analysis at the Popple Lake gravel pit.

The sidewall of the Tilden sandstone pit. It's hard to see, but note the lack of crossbedding in the sandstone.

Trace fossils in the rocks at the Tilden site. These are probably burrows made by ancient worms or worm-like marine creatures. These were the most common fossil I saw there.

Aaron's hand showing hyolithid fossils. These were also fairly common, as were brachiopods.

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