The hydrovolcanic eruptions that result from the interactions between basaltic magmas and water produce pyroclastic rocks with distinctive characteristics seen in this photograph showing a close-up of rocks exposed in the walls of a typical tuff ring on the island of Tenerife. Fuel-coolant like explosive fragmentation of the magma produces a high proportion of very fine grained, glassy material, which rapidly alters in the warm, wet environment to form the yellowish palagonitic tuff making up the most of the matrix of the rock. Ill-defined layers of angular fragments of fresh grey basalt lava are also present. Each layer was probably the product of an individual explosive blast. (Section 9.9.1).

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