Hydraulic fracturing,more commonly referred to as fracking, is a process intended to extend oil reserves in North America through the unconventional extraction of shale oil (Schrag et. al, 2007, pg. 372). Oil shales are extremely tight source rocks that are not permeable enough for oil to be pumped out directly, thus requiring alternative and extreme extraction methods (p. 372). In order to extract shale oil, a high pressure fluid usually consisting of chemicals and sands suspended in water, is injected to create cracks in the deep rock formations (pg. 373). This technique is extremely destructive.
Schrag, D., Field, C., & Thompson, L. (2007). Earth’s Changing Climate. Habitable Planet,352-382. Retrieved September 25, 2014, from http://www.learner.org