Physical Geology Complete Practice Exam 2026

Shield volcanoes. Hawaii’s volcanoes are built from many long, lava flows of low-viscosity basalt that spread out over broad areas, forming gentle, shield-like profiles rather than tall, steep peaks. This effusive eruption style is driven by magma that is relatively low in silica, common at hotspots like the Hawaiian location under the Pacific Plate. The result is large, wide volcanoes such as Mauna Loa, Mauna Kea, and Kilauea. By contrast, other types—scoria cones form from single, explosive bursts creating small, steep piles; composite volcanoes combine viscus lava and tephra to build tall, layered peaks at subduction zones; volcanic domes come from highly viscous magma that pushes up into rounded, moundlike shapes—are not the dominant forms in Hawaii’s volcanic landscape.