The search for oil occurs in geological sediments, as opposed to volcanic rocks. Several processes are involved in the creation of sediments. First, the inland continental volcanic rock is continuously being weakened and eroded by weathering processes (mechanical (through water, ice and wind) and chemical erosion). Secondly and simultaneously, the eroded material is being transported by water, ice and wind and gradually the material may be broken down into smaller pieces (from boulders to gravel, to sand, to silt and finally to clay). When finally ending up in calmer environments, the material is settling out and falling to the bottom (as sediments). Here it will start forming.
