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Wednesday, January 26, 2022

Allegheny Plateau - Day 57

  After I hiked this part of Ohio in 2009, I wrote an article for the North Star entitled, "In Ohio there are No Hills." You and I may find this difficult to believe after seeing our last climb of the afternoon. We started down at the bottom of the valley where you can't see, but can only guess at how far down it is. (500 vertical feet down there.) hiker climbing a hill

Bill likes to generate an elevation profile. It was the same down the other side to the car. Only the down was on a washed-out gully that used to be a skid road. The red dot at the top was us, and the black dot at the bottom was the car. Also 500 feet down.
elevation profile


But while we were at the top there was about a quarter-mile of absolutely flat walking. That is the Allegheny Plateau. All the land in this unglaciated portion of Ohio (and W Virginia, Pennsylvania and New York) was a high somewhat flat area. It severely eroded. In Ohio, that means steep valleys with sharp peaks that remain at or near the elevation of the plateau. Get the picture? No hills, only valleys! Here's one pretty much all by itself, instead of layered in never-ending steep slopes for the trail to cross. sharp pointed Ohio hill

A couple of days ago, I talked about Ohio Shale. But we've also been seeing limestone- more specifically dolomite which is limestone where the calcium has been replaced by magnesium. I was trying to figure out this jumble of kinds of rock that seemed to be appearing with very little sense.

However, today, we walked through Davis Memorial, a really special place where lots of geology is visible, and many rare plants grow. Since January is not a great month for plants, I concentrated on geology.

The longest fault line in Adams County is 6 miles long, and you can see it in the Davis Memorial. On the left is Peebles Dolomite- the curvy rock. On the right is Greenfield Dolomite- the blocky rock. But this fault line is tilted. The Peebles was laid down before the Greenfield. I say "laid down" because these are both sedementary rocks. Adams County Ohio fault line

Later in the afternoon, we saw a cliff that presents things in their natural order. Peebles Dolomite on the bottom, Greenfield Dolomite above that, and Ohio Shale on the top. I think the thicknesses here are somewhat less than in other places, but I finally "got it." The type of rock we are seeing on any given roadside or trailside has to do with how far below the ancient plateau we are. Allegheny Plateau layers

Nikki hiked with us again today, and we had a blast. Some of the formations in Davis Memorial are very cool. Peebles dolomite cliff

End of the day- four hikers, happy that there were no more valleys to face today. hikers

And plants? I saw a couple of rare ones when I was at Davis Memorial before, but I HAVE to come back some time in spring and get some kind of tour from a real botanist. Nikki has a book about the area, and there are all kinds of plants and even ecosystems here that I know nothing about. A hanging prairie? How cool is that?

Miles today: 15.9. Total miles so far: 809.6 Over 800

See Happy Trails with Ben

1 comment:

vanilla said...

Nuce going! Me? Too cold to set foot out of the house.

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