A rock outcrop exposes a layer of obsidian overlain by volcanic ash and a layer with fragments of lapilli.What rock composition and eruptive type fits this description?
A)basalt erupted from a cinder cone
B)basalt flows and interbedded andesite deposited on a shield volcano
C)andesite and basalt erupted from a stratovolcano
D)rhyolite erupted in violent pyroclastic eruptions

Question

Quizplus · Accepted Answer

The presence of obsidian and volcanic ash in the lower layer suggests that a violent pyroclastic eruption occurred, which is commonly associated with rhyolite magma. The upper layer containing lapilli indicates another explosive eruption, with the lapilli being fragmental material ejected from the volcano. Therefore, the best fit for this description is rhyolite erupted in violent pyroclastic eruptions.

A Rock Outcrop Exposes a Layer of Obsidian Overlain by Volcanic