Depths on the ocean floor are also difficult to discern. Have students look in an atlas or map of the seafloor to determine these depths. Divide the width of the map among your group so that each person will be making a profile of one part of the entire length. Decide what the maximum and minimum elevations will be along the 40th parallel. Make a vertical axis on your graph paper which has these as the high and low points.
Horizontal axis is distance.
Mark the longitude along the bottom of the graph paper. Make sure your vertical axes all match up so that you can later glue them all together. Lay your graph paper down along the 40 degree latitude line. Beginning on the left side of the map, find the elevation of the surface of the earth and place a small dot directly below it at that exact elevation. At every point where the elevation changes mark it with a dot in the same manner until all your group is complete. 6.