Place

Coal Vein Trail Post 3: Bentonite

A cracked area of grey clay.
Bentonite Clay

NPS Photo

Quick Facts
Location:
Coal Vein Trail
Significance:
Trail post 3 on the Coal Vein Guided Nature Trail

Historical/Interpretive Information/Exhibits

Notice the sediment on either side of the trail. Fifty-Five million years ago, volcanoes in the Rockies spewed out ash that blew east. At that time, this area was a vast, tropical swamp. The ash settled in wet areas and became bentonite clay. 

Bentonite looks like popcorn when dry, but becomes sticky, slick mud when wet. It can absorb up to five times its weight in water. Known as the mineral of one thousand uses, it is used to seal landfills and ponds, to make cat litter, and much more.
Stay to the left to continue on the guided nature trail. Take the right on the cutoff trail to avoid a section of trail with very steep stairs. You will rejoin the guided nature trail near post #11. 

Theodore Roosevelt National Park

Last updated: July 30, 2021