NX is the number of rows of data per grid. NY is the number of columns of data per grid. FORM is a format flag. The routine contour will read in these data and draw a crude contour plot of the layer with their proper orientation. Contour requires Motif to compile and run.
All values are in feet with depth being positive downward.
Each grid extends to all edges. Any region of a grid that intersects another is a zero thickness region i.e. the two grids have the same depth values.