Sunday, August 3, 2014

Where to see metro geology, part 6: odds and ends

And now, to complete, more or less, my other series:

I've already hit most of the best places to see Twin Cities bedrock geology up close, and there isn't really much need to flog this further. So, to wrap up things, I'm collecting a few stray thoughts on other areas. There is one other location that is supremely worthy of its own post, and if you are tuned in to the local fossil-hound scene you can guess exactly what it is, and also why there's not much of a point in discussing it now. Thus, the Brickyard of Lilydale will wait.

Previous entries:
Lock and Dam 1/Ford Bridge area
Minnehaha Regional Park
Coldwater Spring
Fort Snelling State Park
Shadow Falls Park

Hidden Falls Park

Now not so hidden.

Hidden Falls Park and adjoining Crosby Farm Park are for the most part below the bluffs, which makes them better places for contemplating the actions of the post-glacial river system than observing the bedrock. You do descend past cuts through the Platteville as you enter the parks; the best place to see the rocks here is along the north entrance to Hidden Falls, because of the sidewalk adjacent to the cut. Coincidentally, the north entrance cut is also where the Hidden Falls beaver was found. If you are there at a time when the vegetation hasn't blocked the view, the Glenwood is reputedly visible. The St. Peter Sandstone is also exposed in all its loose sandy glory. Aside from the beaver, Hidden Falls' major claim to lasting geologic fame is serving as the namesake for the creamy center of the Platteville Formation, the Hidden Falls Member (Sloan 1956).

Shoot, just a little too late.

The goat trails

If you are not of the persuasion who likes to wander wooded bluffs looking for rocks that are perfectly visible elsewhere, you would probably be happy calling it a day with Minnehaha Park or Shadow Falls. I can't say this is a terrible decision; for the most part, it's kind of an elaborate way to get exercise. Perhaps the most interesting area is the lowland south of the Short Line Bridge in Minneapolis, where the Platteville is exposed to great effect. This area is also of historical interest, because it is along the old Winchell Trail. If I recall correctly, there was once a quarry here (the Twin Cities were once laced with quarries in the Platteville Formation). It's wise to keep your eyes open if you are exploring a goat trail; it's not uncommon for trails to be blocked by fallen trees and branches, the still air encourages mosquitoes, and occasionally you may stumble across a makeshift camp.

Another one of those photos I can always find a use for.

Washington Avenue bluffs

The Washington Avenue bluffs got their day in the sun back in January (which admittedly would be a short day in the sun). I will simply repeat a photograph which explains my dislike of the site. The one great advantage would be that if something happens, you're right next to medical facilities.

Looks like a great idea!

Honorable mention:

Dayton's Bluff

There is fantastic geology exposed at Dayton's Bluff, only you can't get to it because of the railroad lines and the fact that it is all on a bluff. The bike path on the other side of Warner Road is a great place to take illustrative photos, though. This site came up briefly before because geological wizard Frederick Sardeson somehow managed to obtain fossils from the St. Peter Sandstone.

Dayton's Bluff plus inconvenient consideration.

Similar outcrops can be seen at closer range next to the Big Rivers Regional Trail on the south side of the Mississippi.

Battle Creek Regional Park

It's a great place for recreation, but geologically you're only looking at the St. Peter Sandstone, and it's probably the most thoroughly enjoyed St. Peter Sandstone in the state, which cuts down on how informative it can be.

St. Anthony Falls

You used to be able to see quite a bit of geology here, with historical significance to boot. That changed beginning with the collapse back in October 1869, and it's unlikely to change back anytime soon. St. Anthony Falls is another place to go for recreation. Bring your imagination and try to think of the city with a roaring waterfall.

References cited:

Sloan, R. E. 1956. Hidden Falls Member of Platteville Formation, Minnesota. Bulletin of the American Association of Petroleum Geologists 40(12):2955–2956.

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