Used for an accumulation, usually conical, of mud and rock ejected by volcanic gases; also for a similar accumulation formed by escaping petroliferous gases.
mud waves
SN
After 1992, use mud AND bottom features. See also ripple marks and submarine dunes.
Of Thermopolis Shale. Overlies a lower black shale member and underlies a black shale member. Surface and subsurface in central N Wyoming and subsurface in central S Montana.