noun
: one of the little heaps that occur on the surface of certain geological strata containing organic matter and that are believed to be due to the escape of gas during early formative stages of the strata
noun
: one of the little heaps that occur on the surface of certain geological strata containing organic matter and that are believed to be due to the escape of gas during early formative stages of the strata
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012