Gravity and Magnetic Survey Uvalde Area Project in Uvalde and Zavala Counties, Texas

摘要

The objective of the field survey was to locate an igneous intrusive mass (basalt) which could be drilled to a depth of at least 5000 feet for the purpose of testing coring and logging techniques. The combination of gravity and magnetic methods was selected as the most suitable means of delineating a basalt mass which would be satisfactory for the drill test. Each of the methods responds to changes in potential force fields which are related to the physical properties of underlying rocks. The force of gravity varies in response to lateral changes of density in the substrata; the magnetic field is affected by lateral variations in the susceptibilities of underlying rocks.