Aerial photo interpretation and mapping - Bayou Meda anticline, Arkansas

Jamey Jones
,
Earth Sciences, University of Arkansas at Little Rock
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Summary

Multi-day project using aerial photography and field observation to map and interpret a megascopic anticline/syncline pair exposed in the Ouachita Mountains of central Arkansas. This exercise involves two classroom days and one field day but could also be completed in the classroom using only the aerial photo and topographic base maps. This project helps students develop their geological mapping and interpretation skills by focusing on both remote and direct observation, hypothesis development, and synthesis of multiple datasets.

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Context

Audience

University of Arkansas at Little Rock ERSC Field Geology I (ERSC 3320), a sophomore-level course intended for second- or third-year geology majors. The class meets weekly for one hour on Wednesdays and four hours on Fridays. Wednesday meetings are typically held in the classroom, and Friday meetings typically involve travel to field locations. The course is team taught with four primary instructors, and two instructors are typically involved in each weekly exercise.

Skills and concepts that students must have mastered

Students should have some familiarity with topographic maps, the Global Positioning System and UTM projection, sedimentary rock description, structural measurement of dipping beds, and a basic familiarity with geological mapping practices and understanding of rock deformation and characteristic structures.

How the activity is situated in the course

This is the second off-campus exercise of the course that follows and builds on exercises in pace/compass mapping, GPS use and mapping, and outcrop description and measurement (see attached syllabus schedule). This project was designed to introduce the students to aerial imagery and its utility as a geological mapping and interpretation aid. The project also integrates all of the skills from previous field exercises and allows the student to use their new knowledge and skills to answer a research-type question and create a geological map and structural interpretation from a relatively small number of field observations and measurements.

Goals

Content/concepts goals for this activity

The overall goal for this activity is for students to integrate remotely-sensed data (aerial photography) with direct observation, description, and measurement of outcrops to interpret the geology of an unknown area.

Higher order thinking skills goals for this activity

This exercise involves analysis of a remotely-sensed dataset (aerial photograph) and development of an initial geological interpretation and hypothesis regarding the structures exposed in the field area. The students are then taken in the field to make observations and collect data that test their hypothesis. Then the students are asked to synthesize their two datasets (remotely-sensed data and direct observation) to develop a single interpretation of the geology and structure of the field area.

Other skills goals for this activity

Other skills emphasized during this activity include drafting practices for geological mapping and cross-section construction and best practices for collecting field observations and measurements in a field book.

Description of the activity/assignment

Students use aerial photography combined with field observation to interpret the geology of a megascopic anticline-syncline pair exposed in the Ouachita Mountains of central Arkansas. This project focuses on the integration of remotely-sensed data with direct observation to develop and test hypotheses regarding the geology and structure of a well-defined field area. Students construct a geological map and cross-section that synthesize their observations and illustrate the geology of the field area.

Determining whether students have met the goals

Students turn in the following components of the exercise:
  1. Geological map – completed geological map on the aerial photograph overlay with unit contacts, unit labels (arbitrary unit labels derived from relative age of marker beds in folds), structural measurements, and structural interpretation (axial traces of folds). The map is to be drafted with contacts and symbols inked and map units colored. A complete map explanation must also be included.
  2. Cross-section – completed geological cross-section of the map area along a north-south line at the same scale as the map with no vertical exaggeration. The cross-section is to be drafted with contacts, labels, and symbols inked and map units colored to match the geological map.
  3. Field books – students turn in their field books to be graded on the quality and completeness of the field notes and how well they incorporated previous comments on their field notes from the instructors.
Students are graded on the geological map (accuracy of contacts, accuracy of locations, structural data and interpretation, general drafting) and cross-section (topographic profile, accuracy of contact location and orientation, bed thickness and structural interpretation, general drafting).

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