Image is from a scan ning electron microscope. Dark blue lines denote seismic reflection profiles and the dashed red line shows the northern limit of sedimentary cover. White lines denote seismic reflection profiles. The Slave-Rae collision.
White lines show seism ic reflection profiles.
Note the strong positive contrast of the rift valley to its surrounding rocks. The reason for the positive anomaly was not understood until the results of our studies in the Great Lakes - the large volume of dense volcanics in the rift valley causes the anomaly.