1. A layer of bubble-free, dense ice found in a glacier. 2. A bluish clay found as a thin, persistent bed near the base of No. 6 coal everywhere in the Illinois-Indiana coal basin.
Related terms:
1. A layer of bubble-free, dense ice found in a glacier. 2. A bluish clay found as a thin, persistent bed near the base of No. 6 coal everywhere in the Illinois-Indiana coal basin.
Related terms: