Shield volcano are cave-like volcanic straights formed by the hardening of overlaying lava. These structures help further the propagation of lava, as the walls of the tube insulates the lava within. Lava tubes can account for a large portion of shield volcano activity; for example, an estimated 58% of the lava forming Kīlauea comes from lava tubes. In some shield volcano eruptions, basaltic lava pours out of a long fissure instead of a central vent, and shrouds the countryside with a long band of volcanic material in the form of a broad plateau. Plateaus of this type exist in Iceland, Washington, Oregon,
Jackson Volcano Jackson Volcano Jackson Volcano is an extinct volcano beneath the city of Jackson, Mississippi, under the Mississippi Coliseum. The uplifted terrain around the volcano forms the Jackson Dome, an area of dense rock clearly noticeable in local gravity measurements. E.W. Hilgard published his theory of an anticline beneath Jackson in 1860 due to his observations of surface strata. The dome contains relatively pure carbon dioxide which is used in oil production in Gulf Coast oil fields. The noble gas data suggests mantle origins with a date of 70 million years for the Jackson Dome intrusion. Geologists have evidence of repeated