A conspicuous sandstone layer outcrops in a cliff, and has the apparent dips shown. Determine the true strike and dip. Draw lines with map traces parallel to the two apparent dip planes. Construct elevation points on both lines. Draw structure contour lines through points of equal elevation.
Strike is simply the azimuth of the structure contours.
Find dip by trigonometry or by cross-section. However, suppose we have two highway cuts or quarry walls that expose a series of layers that are so similar there is no way to correlate beds from one exposure to the other. Possibly none of the layers correlate, but the rocks are uniformly dipping. We can solve this problem by realizing that we are trying to find a plane parallel to two given lines. If the lines actually intersect we can use the lines themselves, if not, we can use two lines parallel to the given lines that do intersect.