How the Hawaiian Islands Were Formed

Hotspot Volcanism

The Hawaiian chain sits above a stationary mantle hotspot. As the Pacific Plate drifts northwest, magma punches through the crust, building volcanoes that eventually become islands. The oldest islands (e.g., Kauai) lie to the northwest; the youngest (Big Island) sits over the hotspot today.

Volcano Types

• Shield volcanoes: Broad, gentle slopes built from fluid basalt flows (e.g., Mauna Loa, Mauna Kea).
• Cinder cones: Steeper, smaller vents formed from fragmented lava (e.g., Diamond Head).

Ongoing Process

Kīlauea and Mauna Loa remain active, adding new land. Meanwhile, erosion and subsidence gradually wear down older islands, creating the dramatic cliffs, valleys, and reefs that define Hawaii’s scenery.