Teaching Strain Theory in Structural Geology Using Graphics Programs for the Apple Macintosh Computer

Abstract

The built-in graphics capabilities of the Apple Macintosh computer make it an ideal tool for instruction in strain analysis. Simple programs written in Microsoft BASIC permit students to apply the rules of simple or pure shear and to synthesize interactively two-dimensional strained objects on the computer screen. Such exercises improve the students' visual perception of strain. We have written three programs which graphically simulate strain. The first program (Strain-Graph) deforms a square, and lines and a circle in the square. The second program (Deform-A-Pic) deforms any picture (e.g., a bed or fossil) drawn in MacPaint. The third program (Shear-Zone) permits simulation of shear zones across which there has been inhomogeneous simple shear. The first two programs allow the user to specify interactively both the amount and type of deformation (either pure or simple shear) that is to be imposed on the screen image, and allow increments of pure and simple shear to be superimposed. The third program allow...