volcanic tuff

Tuff, tuf, n. generally volcanic tuff, the name given to the comminuted rock-dbris ejected from a volcanic orifice.

At one place I noticed an Indian trail leading up a ridge apparently consisting of volcanic tuff.

It grows here and there in groups at high altitudes, on decomposed volcanic tuff.

The great mass of the surface of the mountain, not specially mentioned above, is volcanic tuff.

The Tank Site specimens range through volcanic tuff, siliceous sinter, escoriated basalt, to a fine-grained basalt.