Power washing is used to clean off any dirt that could be on the rock or outcrop, so that the geologist can observe and document the geology. A jet of water from a pressure pump is used to loosen and remove most clays or dirt.
Once the rocks have been cleaned it will make it easier for the geologist to see what types of soil and rocks, they will be dealing with. The geologists will also be able to take better samples of the rock without any sand, or gravel interfering with the sample.
