Basic Lava Cone or Lava Shield. Sometimes, the basaltic lava having low silica content flows out quietly and gives rise to the formation of a shield. The lava flows out quietly around a central opening. In course of time, it builds up a shield-shaped volcano with a wide base and low slope. It cools as thin horizontal sheets. Probably the best examples are the Mauna Lao shield volcanoes of the Hawaiian Islands.