Isostasy and crustal thickness

Audrey Huerta
Central Washington University,
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Students will write a matlab code to calculate crustal thickness of 5 locations. Calculations will use topography (determined by running a matlab script that creates a clickable map) and nominal density values, and the assumption that the crust is in airy isostasy. Students will then run another script (with clickable map) to determine the actual crustal thickness of the locations. If the calculated and actual thicknesses are significantly different, students will discuss possible geodynamic reasons for the non-airy crustal thicknesses.

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Learning Goals

Students learn to manipulate and code algebraic equations.
matlab is used to make the same calculation multiple times.
Students learn the concept of airy isostasy, and the limitations of the concept.

Context for Use

This project is appropriate for students with college-level algebra skills, minimal matlab skills (plotting, equation coding), and some background in geodynamics (to understand mantle contributions to topography).

Description and Teaching Materials

Students are provided a handout describing airy isostasy, and the associated equation. They then code-up the equation and estimate crustal thickness of five locations, using elevations determined from a clickable map (provided). Students then compare the calculated thicknesses to actual thicknesses of those locations (also determined from a provided clickable map).
In locations where calculated and actual thicknesses are significantly different, students discuss possible geodynamic processes and/or conditions that could be in play.
student handout for Airy Isostasy (Acrobat (PDF) 205kB Oct6 15)
crustal thicknesses ( 239kB Oct6 15)
Plotting crustal thicknesses (Matlab File 922bytes Oct6 15)
global topography data ( 239kB Oct6 15)
plot topography (Matlab File 974bytes Oct6 15)

Teaching Notes and Tips


students hand in scripts that correctly calculate crustal thickness assuming airy isostasy
students hand in table of 5 locations with calculated and actual crustal thickness.
students use geologic and geodynamic principles to discuss possible processes/conditions that could explain significant differences between calculated and actual crustal thicknesses.

References and Resources