intrinsic change in, [283], [284], [337], [338];
what they are not, [185-187], [373];
zonal distribution of, [188], [189];
departure-points, [190];
dependent on general topography, [191];
of later origin than main features, [191], [247];
kinematic character of, [281-303];
effect on, of illumination, [284];
drawings of, numerous and
consecutive, [286];