by Squirrel Girl » Aug 16, 2014 5:48 am
It is unlikely to have a natural cave adjacent to talc bedrock. Talc is not a soluble mineral the way calcite (which makes up limestone) is.
The reason there is all that water back there, is because the miners intersected the water table. The water table is the level in the earth where below, all the pores in the rock are filled with water. Above the water table, there can be some water, but there's air in there, too. So if a mine gets dug below the water table, water will leak in. While the mine is operating, the miners use a pump to keep the operations dry. When the mine is abandoned, the water then leaks in. If that seems odd to you--it's really all around you. The water table (in non-arid, non-desert conditions) mimics the land surface, but it's a little deeper under the hilltops. But in stream valleys, the water table comes up to the surface. Think about the time there's been a dry spell. It hasn't rained for the longest time, but there's still water flowing in the streams. The water is lower, but the streams still run. That's because all that ground water seeps into the streams straight out of the rock or soil. It's called "base flow." And that's what's happening in the talc mine. A spring is just a place where all that water gets concentrated in one particular spot. It's where the rock doesn't allow the water to flow very well, but a fracture (potentially) is a conduit where water has an easier way to flow. In karst terrain, fractures in limestone can dissolves into factures that can grow into caves.
So, in some way, the water in the talc mine is similar, but in other ways, it's very different. Go out and enjoy the mine!
Barbara Anne am Ende
"Weird people are my people."