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Structural Geology Computations in a GIS

Peter L. Guth Dept Oceanography, US Naval Academy
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This is a partially developed activity description. It is included in the collection because it contains ideas useful for teaching even though it is incomplete.

This activity was selected for the On the Cutting Edge Reviewed Teaching Collection

This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are

• Scientific Accuracy
• Alignment of Learning Goals, Activities, and Assessments
• Pedagogic Effectiveness
• Robustness (usability and dependability of all components)
• Completeness of the ActivitySheet web page

GIS program allows computation and display of three point problem and contact tracing across topopgraphy. It helps students visualize how terrain and stratigraphy interact.
GSA Poster (Acrobat (PDF) 3.4MB Nov5 04)

Learning Goals

Content/Concepts:
Planes in 3D.

Geologic Skills:
Three point problem.

Higher Order Thinking Skills:
Visualizing data and maps.

Other Skills:
Using GIS.

Context

Instructional Level:
Any level.

Skills Needed:
Maps.

Role of Activity in a Course:
Virutal field trips.
Field data collection.
Compilation of field data.

Data, Tools and Logistics

Required Tools:

Logistical Challenges:
Understand GIS and computers, and use program before exposing students to it

Evaluation

Evaluation Goals:

Evaluation Techniques:

Description

Outcrop patterns of faults, dikes, and sedimentary beds reflect the interplay of 3D orientations and the topographic land surface. A key task for geologists, and hence geology students, requires extrapolating from the depiction on a geologic map to a visual model of the topography and geology. A related task starts with a measured orientation, and requires estimation of where the structure projects on the map. Two simple geometric problems from the basis for much of this visualization: the three point problem, and the projection of a measured dip and strike across topography. A geographical information system (GIS), starting with a digital elevation model (DEM), can easily manipulate both types of data with a variety of base maps: scanned topographic or geologic maps, air photos, or satellite imagery. Given suitable large scale digital base maps, students can digitize contacts and compute attitudes on the computer, observe 3D representations of the terrain and rotate them to any desired orientation. The MICRODEM GIS implements these geometric operations, in both a simple teaching version that emphasizes only the geometric relationships, and as part of a full-featured GIS program. MICRODEM can be used in preparation for going to the field to help students learn to visualize, for 3D stereo virtual field trips on the Geowall, and taken into the field on a tablet PC for improved mapping efficiency. GPS tied to the PC removes the tension students feel in locating their position on the map, and lets students can concentrate on matching the map features to the terrain in front of them and thinking about the geometric structures of the geologic features. In addition to improving geometric perceptions, using the GIS introduces students to valuable technology.