[Rockhounds] Giant Sinkhole Opens Up In South Dakota and Exposes Abandoned Mine

[gary brown]

All of us geology students at SD Tech knew about the hazards of building over the gypsum deposits.  It's a REALLY thick band that pretty much encircles the entire Black Hills.  I've got some nice chunks in my collection.

GcB

-----Original Message-----
From: Rockhounds <rockhounds-bounces at rockhounds.drizzle.com> On Behalf Of Tim Fisher
Sent: Saturday, June 20, 2020 11:31 AM
To: 'Rockhounds at drizzle.com: A mailing list for rock and gem collectors' <rockhounds at rockhounds.drizzle.com>
Subject: Re: [Rockhounds] Giant Sinkhole Opens Up In South Dakota and Exposes Abandoned Mine

If you saw the photos there's a car in the mine that looks like it crashed through the ceiling. I don't know cars well enough to know what it but it looks pre-1960s to me. So maybe it isn't "new news" that there was a mine under the property. I've seen really stupid housing built on the Oregon Coast, some on cliffs or old landslides that the permitting agencies and developers HAD to know would collapse within a couple decades. One that I was involved in the aftermath of only took 10 or so years before the houses were tilting towards the beach and everyone was suing everyone else. Another newish development is bound to sink into the ocean sooner rather than later, it's built on a sand spit at the mouth of an estuary. And they knew the story of the Bayocean resort 50 miles or so north also built on a sand spit that got swallowed up in the 1950s.

Tim Fisher
Http://OreRockOn.com 
Email nospam at orerockon.com



-----Original Message-----
From: Rockhounds [mailto:rockhounds-bounces at rockhounds.drizzle.com] On Behalf Of Kreigh Tomaszewski
Sent: Saturday, June 20, 2020 7:08 AM
To: Rockhounds at drizzle.com: A mailing list for rock and gem collectors
Subject: [Rockhounds] Giant Sinkhole Opens Up In South Dakota and Exposes Abandoned Mine

About a dozen houses in Black Hawk, South Dakota, were evacuated after a sinkhole opened under the Hideaway Hills development. The ground started to give way on the 27th of April and while it has left a lot of uncertainty for the locals, the situation has led to a unique discovery. The residential homes were built over an abandoned gypsum mine.

The authorities are already trying to figure out how this could’ve happened but in the meantime, explorers of a local caving group called *Paha Sapa
Grotto* decided to take a look inside.

The *Paha Sapa Grotto* is a subchapter of the National Speleological Society and is a world leader in caving science, exploration, and conservation. “When we heard about the sinkhole, we knew it was on a geological unit that could potentially have caves in it,” Nick Anderson, a member of Paha Sapa Grotto, told *Bored Panda*. “We also knew that county emergency management wouldn’t have much experience in this area so we offered to help to determine the scope of the problem.”

https://www.boredpanda.com/sinkhole-south-dakota-black-hawk-old-gypsum-mine/
_______________________________________________
Rockhounds mailing list
Subscription Services:  http://rockhounds.drizzle.com/mailman/listinfo/rockhounds_rockhounds.drizzle.com
List Usage Policy: http://Tomaszewski.net/Kreigh/Rockhounds/Rockhounds.shtml


_______________________________________________
Rockhounds mailing list
Subscription Services:  http://rockhounds.drizzle.com/mailman/listinfo/rockhounds_rockhounds.drizzle.com
List Usage Policy: http://Tomaszewski.net/Kreigh/Rockhounds/Rockhounds.shtml