Tuff

Definition and stakes

Portrait of H. B. Guppy H. B. Guppy,  Observations of a Naturalist in the Pacific Between 1896 and 1899…

“ Each bed is exposed at the foot of a tall cliff of agglomerate forming a line of escarpment along the mountain-side. The larger fragments making up these tuffs are usually from 2 to 3 millimetres in size; but the process of palagonitisation is not complete; and we find inclosed abundant angular pieces of a dark fresh tachylyte-glass, finely vesicular, and fusing readily in the ordinary spirit-lamp flame. The tuffs contain little or no lime and seemingly no organic remains. ”
Source: Gutenberg

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