Pyroclastic Fragments and Deposits

Abstract

Pyroclastic fragments, also known as pyroclasts (Schmid, 1981), are produced by many processes connected with volcanic eruptions. They are particles expelled through volcanic vents without reference to the causes of eruption or origin of the particles. Hydroclastic fragments are a variety of pyroclasts formed from steam explosions at magma-water interfaces, and also by rapid chilling and mechanical granulation of lava that comes in contact with water or water-saturated sediments (Chaps. 4 and 9). We focus upon pyroclastic material in this chapter, but much of the discussion also applies to hydroclastic deposits.