Lava
Block lava flows

Block lava flows are typical of andesitic lavas from stratovolcanoes. They behave in a similar manner to ʻ a ʻ ā flows but their more viscous nature causes the surface to be covered in smooth-sided angular fragments (blocks) of solidified lava instead of clinkers. As with ʻ a ʻ ā flows, the molten interior of the flow, which is kept insulated by the solidified blocky surface, advances over the rubble that falls off the flow front. They also move much more slowly downhill and are thicker in depth than ʻ a ʻ ā flows.
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