FIELD METHODS IN EXPLORATION/ENVIRONMENTAL GEOPHYSICS

One of the disadvantages of teaching geology and geophysics in Louisiana is that most of our spectacular geology is not visible from the surface. Many students, who have never traveled outside of the state, have not seen rocks, minerals, or mountain ranges outside of a classroom. Thus, we miss the opportunity to excite and attract students by taking them out into the field to see geology all around them.

Geophysical methods are a non-invasive and relatively inexpensive means of examining the shallow subsurface. They can be readily applied to many local geologic and/or anthropologic features. The objective of Exploration and Environmental Geophysics is to show how geophysical properties, such as seismic velocity, gravity, magnetics, and resistivity, are used to characterize the subsurface. Our seismograph, gravimeter, electrical resistivity meter, and ground penetrating radar systems are used to provide hands on learning. During the weekly laboratory session, students do seismic and resistivity surveys on campus near the Mississippi River levee to look at subsurface stratigraphy/structure, a ground penetrating radar survey across the 5000 year old LSU Indian Mounds to look for artifacts, a combined gravity and ground penetrating radar survey on LSU’s Memorial Tower to image the service tunnel running underneath, and a combined resistivity and GPR survey across a former Superfund Hazardous Waste site. This class attracts upper level undergraduate students and first year graduate students from Geology and Geophysics and Petroleum Engineering.

Digital recording allows students to do basic data gathering and processing, such as common offset shots, filtering, and multiple gathers. Learning by doing develops critical thinking and problem solving skills. For example, students learn how to squeeze valuable information out of noisy data. It also is inherently more exciting than static presentations by an instructor in a classroom. Moreover, a field project with an informal atmosphere and a team spirit promotes greater interaction between students and the instructor. Availability of both electrical and seismic equipment allows students to see first hand the strengths and weaknesses of each technique for any given subsurface study. Emphasis is also placed on development of proper field notes.