This is a very simple problem if we recall that we can find the strike and dip of any plane given three points on the plane. We simply need to read the elevations of points from the topographic map. Actually, the problem is often even simpler than that, because we can often select the points we use, and if two of them have the same elevation we can draw a structure contour through the points with no other constructions necessary at all. However, it's a good idea to cross-check the results using other data since geologic structures are rarely smooth planes. Find the strike and dip of the sandstone layer from the map at left.
Outcrops are in brown.
For pairs of points at the same elevation we can draw structure contours directly. The more points on a line, the better. In other areas we can use the three-point method to find structure contours. Find dip by drawing a cross-section or by trigonometry. Some Additional Hints Real geologic structures are rarely planar over very long distances.