Volcanos and Magma/ Glaciers and Water

In answer to the questions "What makes lava rise and overflow from it's crater?", and "What causes some volcanos to erupt with explosive force from time to time?", one geologic encyclopedia gives the following answer: "The answer to both questions is water, in the form of steam." (EA, p. 153). We all know what happens when we boil a pot of water and put a lid on it.

As the rock melted below glaciers, it slowly heated the earth; the ice at that spot began to melt and seep into the earth. As the water came in contact with the molten rock, steam was produced. This exerted tremendous pressure beneath the surface, forcing the earth up further. The cycle continued until enough pressure was exerted to expel the gases, lava and earth at the weakest point.

A cycle was established- each "fed" the other: the magma slowly heated the glacier and melted some water; the water seeped into the earth and came into contact with the magma which produced steam. The pressure thus produced pushed the magma closer to the surface, melting more glacial ice, which in turn, seeped into the earth and came in contact with the magma. This continued. Massive glaciers were melted quickly, not over long periods of hundreds and thousands of years.

"The amount of water released during an eruption is amazing. At the height of its activity, Paracutin produced 16,000 tons of water daily, as well as 100,000 tons of lava.." (EA, p. 153). An example, on a much smaller scale, of what occurred during the glacial period: "Direct observations show clearly the effect of exterior water on volcanic eruption. Snow melting in a volcano's crater, or heavy rain over the summit area during a period of activity is sufficient to trigger off renewed eruptions. This process was observed in 1915 at Lassen Peak, California and in Vesuvius in 1926." (EA, p. 153 154.)

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