Drilling of a 12,000-foot-deep scientific well has been completed at Cajon Pass in southern California to measure crustal properties, to determine crustal structure, and to better understanding the generation of earthquakes along the San Andreas fault. A joint effort of the National Science Foundation (NFS) and the U.S Geological Survey (USGS), the well was begun in November 1986, and is one of the first projects to be undertaken in the new national Continental Scientific Drilling Program. This program aims to enchance our knowledge of the compostiion, sturcture, dynamics, and evolution of the continental crust and of how these factors affect the origin and distribution of mineral and energy resources and natural phenomena such as volcanic eruptions and earthquakes.