We can then find the strike and dip of the plane using methods we have already developed. Examples Find a Plane That Contains Two Intersecting Lines 1. Given the two plunging lines, find the plane that contains them both. Construct the map trace and elevation points for each line. Draw structure contour lines through points of equal elevation.
Strike is simply the azimuth of the structure contours.
Find dip by trigonometry or by a cross-section. In the next example, the two lines don't intersect. For example, we might observe metamorphic foliation on two dipping joint planes, but not have enough surface relief to determine the dip. Also, we can't tell which foliation trace on one joint corresponds to any on the other joint. Nevertheless, we know the foliation has a strike and dip.