Fracking uses high-pressure mixtures of water, sand or gravel and chemicals to crack rock formations and release oil and natural gas deep underground.

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Shale gas is natural gas that is trapped inside shale rock and is extracted by using a technology called hydraulic fracturing, where highly pressurized water mixed with sand and chemicals is used to crack open rocks.

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Rather, as a consequence of injecting water and sand into the shale formation to crack the rocks so gas and oil will flow, massive amounts of waste water comes back to the surface with significant amounts of contaminants as a result of leaching out salt, heavy metals and trace amounts of radioactive materials from the rock formation itself.

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Fracking involves injecting water, sand and some chemicals deep into the earth to crack shale rock, which frees oil and gas.

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Hydraulic fracturing, or fracking, pumps millions of gallons of water mixed with fine sand and chemicals deep into oil and gas wells to crack gas-bearing rock.

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They also get a crack at pitching their ideas to investors on Demo Day, an event that lures venture capital's Sand Hill Road crowd and every prominent angel investor in the Valley.

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