A vocabulary of landscape — a landscape of words
975 entries
bentonite
A highly absorbent, swelling clay formed from the weathering of volcanic ash. Bentonite can absorb several times its weight in water, expanding dramatically and becoming slippery, plastic, and nearly impervious. Wet bentonite on a trail or road is one of the most treacherous walking and driving surfaces in the West — it clings to boots in heavy, accumulating slabs and turns roads into impassable grease. Dry, it cracks into a mosaic of hard, pale flakes.
Etymology
Named for Fort Benton, Montana, near the location where it was first described in 1898. The clay is associated with Cretaceous-era volcanic ash deposits across the Western Interior.