Fracking: Danger to earth or boost to energy industry? August 16, 2013 -- Updated 1430 GMT (2230 HKT) Hydraulic fracturing, known as fracking, has split public opinion and led to protests in England. So what is it? Explore CNN's interactive to find out. Shale wells go thousands of feet deeper than traditional natural gas wells. A well is typically drilled between 5,000 to 20,000 feet into the earth's crust, then turns 90 degrees and continues horizontally for several thousand feet to where it is believed the shale contains natural gas. A mix of water, sand and chemicals are pumped into the well at high pressure to create long narrow cracks or openings in the earth through which gas can escape. The sand particles keep the fissures open allowing for natural gas to escape from the shale and flow into the well. The gas, along with the wastewater, is drawn back up the well to the surface where it is processed, refined and shipped.