Basalt Floods. The theory behind such occurences and the effects and evidence of such floods on the earth.

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Basalt Floods

Millions of years ago, lava flows poured molten rock over huge areas of the

world. These eruptions, known as basalt floods, hurled noxious gases fro

Earth's interior into the atmosphere. Toxic clouds ravaged the environment and

may have triggered mass extinction. The weathered remains of flood basalt can

still be seen around the world. but scientists do not yet understand the cause

of such vast eruptions. It is such a mystery that a basalt flood could burst

from the Earth tomorrow undetected.

Basalt floods smother whole regions of the Earth in molten rock. They are

released when immense volumes of magma apply pressure to the Earth's rigid crust

until it cracks around huge, violent fountains of lava. It can take over a

million years to exhaust the magma supply completely and end the flood.

The last major flood eruption covered Washington and Oregon 16 million years

ago and spread over 77,000 square miles.

It solidified as the Columbia River

Plateau and even after 16 million years of erosion, the flood basalt still cover

an area larger than the state of New York. The Deccan Plateau in India, which

erupted around 65 million years ago, is twice that size.

One possible cause of flood basalt is magma plumes. Magma forges a path from

chamber deep within the Earth's hot mantle and forces it way through the crust

n fissure that are sometimes over 50 miles long. There are no big bangs- gases

simply bubble through the highly fluid lava without blowing it apart. Each

fissure disgorges sheet of molten rock above ground that may smother up to

14,000 square miles of the surface.

Successive eruptions expel layer upon layer of basalt - in some places the

plateaus lie three miles thick. Flows of hot rock annihilate all life...