Figure 5. This schematic diagram shows how the different rocks shown in Figures 1-4 might have formed in a volcanic environment. Flow-banded rhyolite solidifies directly from lava in the volcano. Explosive eruptions produce chunks of rhyolite and other volcanic rocks that land near the vent to form a breccia. As rain or streams wash the debris downslope it is sorted into layered deposits such as tuff. Finely pulverized rock debris may be blown high into the atmosphere only to rain down as accretionary lapilli farther down wind. If such volcanoes really did exist in Maine, they have been long since eroded. All that remain today are clues preserved in the rocks that indicate their volcanic origin.
Last updated on October 6, 2005