Shield volcanoes are produced by the accumulation of fluid basaltic lavas and exhibit the shape of a broad, slightly domed structure that resembles a warrior’s shield. Most shield volcanoes begin on the ocean floor as seamounts, a few of which grow large enough to form volcanic islands. In fact, with the exception of the volcanic islands that form above subduction zones, most other oceanic islands are either a single shield volcano, or more often, the coalescence of two or more shields built upon massive amounts of pillow lavas. Examples include the canary islands, the Hawaiian islands, the Galapagos, and easter island. In addition, some shield volcanoes form on continental crust. Included in this group are several volcanic structures located in east Africa.