LiDAR shows where old mines are collapsing in the Appalachian Mountains 

They are something else. When you look at them with this sort of digital topography there are lots of "humpback" looking features. Big Hill on 220 is particularly interesting. Low Moor is really cool from the standpoint of landscape evolution--the river has some old terraces and meander cut-offs way up in town. You could find "river jack" cobbles way up on the hills today and wonder how on earth they got up there.

I have wondered how prevalent big but subtle movements like this are. I guess you can actually see them in a drier place without trees everywhere! Most Appalachian slopes that experience large but deep, gradual movement appear to be susceptible to just that--large and slow movement. Plenty of huge slope failures have a stream eroding their toe, and they just creep along. I'm not sure if there is enough potential energy in the landscape to make more rapid large, deep failures, but nobody would want to find out, either. I was recently told about a bridge piling with anchors going 80 ft deep that was moving peacefully along on top of a huge landslide. The slide was apparently 115 ft deep.

@TheGeoModels not sure if this will work on here. If it does, it's on Google maps, horseshoe shaped above the open pit mine. Very deep and obvious from the ground. ⁦39°18'10"N⁩ ⁦119°39'25"W⁩

What yall looking for out there (if you can divulge)?

@@TheGeoModels Ah, well, there was an old gas pipeline that was put in back in the 40s(?). It was gonna get replaced so we were doing a depth to bedrock study to see where competent bedrock started. Basically they needed to know where they could blast or just use a dozer. Some areas we did them in, I don't know how you would get a dozer back there. Also, carrying a car battery up or down those slopes was not fun. Also, those adits sound dangerous. I don't know if the Virginia Survey has closed them off, but a buddy of mine and I explored some old small mines around Dadeville, Alabama which were not marked or closed off, but abandoned. If you fell down into one of those, you're not coming back out. I have a video of one where we dropped a GoPro down in one. If you look closely towards the end, you can see deer bones at the bottom. Don't wander the woods at night.

I guess it's nice to ground-truth features, but the lidar is def a game changer. Lots of structural geology work in Appalachia is legitimately better done with lidar, at least from a qualitative standpoint in heavily forested areas

@@TheGeoModels From a practical standpoint as well, I expect in some hollows and low points you might have trouble getting enough satellite fixes to achieve much with GPS. I presume your LiDAR work doesn't require soaking in DEET and other bug juices and you can wear flipflops. But as a bonus being in the outdoors would you get much of a suntan now maneuvering under and through those trees and bush, so maybe low SPF suffices?

I do my best! Glad you enjoyed it!

It is on The National Map Viewer hosted by the USGS. Just Google for it. When the viewer opens, you have to select the Hillshade layer from the drop down menu. The Layer drop down is like a little stack of plates or cards or whatever. Select hillshade, and you can see a lot. They don't have slope shade, so the northwest ridges are bright, but it's still awesome.

No, those are from deeper down in the Earth where more stress can accumulate and then slip loose. Most are a few miles deep, though some are only a couple of miles. The slides in this video still aren't too big in the greater scheme of things, and they probably didn't move all at once...I'd actually be interested to know! Check out Rattlesnake Mountain in Washington State; it's a recent landslide sort of like the ones in the vid. It moved over a period of time--it was fast geologically, but was still a slow process. Eastern North America has some tectonic stress on it. It's not huge, but there's enough there to make the Earth's crust slip and budge now and then. The fact that the Appalachians have so many old geologic structures in them allows the crust places to slip.

A surprising number, to say the least.

Just about every slope in that area is ready to move a little bit with just the slightest disturbance.

That is very true.

No, that's over on the western edge of the Blue Ridge, sort of west of Galax along the New River. It's a different group of rocks with a slightly different origin for the ores. This area is the "Oriskany ores." It's associated with the contact between a limestone layer and a black shale layer in the Appalachian Valley and Ridge.

I'll keep it in mind!

@@TheGeoModels I enjoy seeing you in your presentations and I like your sketches too.