Intrusive Rock Deposit
These photographs were taken of the Canadian shield, where glacial erosion expose the intrusive igneous rock. Narrow, white zones are dikes of secondary intrusion. Exceedingly long features, 11, 12, and 13, are (shear) zones of softer, ground material, which have been preferentially weathered. The three dimensional illustration (Hamblin and Howard, 1975) shows how persistent these shear zones can be. Photo from Mollard, J.D; J.R. Janes (1984) Airphoto Interpretation and the Canadian Landscape, Energy, Mines, Resources, Canada.