Elasmia cave was created in 2011.

Kansas

It is made by water erosion as it passes through the limestone..

10cm of blubber for warmth

bent tusks to act as a snow plow

small ears to keep in heat

thick layer of fur or warmth

new veins to stop blood from freezing

ridged bumpy teeth to eat frozen vegetation

That abstract thought in humans occurred much earlier than once thought.

Probably not! I can't speak for specific caves but as a general rule caves in limestone are not gem-stone mineral sources.

It's important too, to differentiate between gem-stones and gem-stone minerals, because the former are simply high-enough quality specimens of the minerals to yield cut ornaments.

That's not to dismiss it entirely: caves formed in marble may hold gem-stone minerals (not the same as gem-stones) if the passages have cut into igneous dykes or been affected by later hydrothermal activity.

There is also the point that you never remove any of a cave's natural contents except in 3 situations: 1) "digging", i.e. clearing silt or boulder obstacles to discover where the passage leads; 2) minimum-size samples for genuine laboratory analysis; or 3) for proper preservation and display when the cave is being destroyed by quarrying or civil-engineering.

So even if the cave holds "gem" minerals... you don't touch 'em!

The Mammoth Cave

Ashoka

Yes it is

694 miles

Cave of Echoes was created on 1996-06-07.

Apparently it was destroyed by vandals.

cave dwellers draw on walls because the draw what is important to them

Mammoth Cave has over 390 miles of passageways.

Mammoth Cave National park covers 52,385 acres.

Mammoth Cave was once used as a tuberculosis hospital.

Mammoth Cave receives over 500,000 visitors each year.

it is a 'karst' cave, i.e. formed by the action of water on limestone.

Furong Cave was created in 1993.