QUICKSAND, in its usual significance, a tract of sand which, without differing much in appearance from the shore of which it forms part, remains perma nently saturated with water to such an extent that it cannot support any weight. Quicksands are most often found near the mouths of large rivers. They ap pear only to be formed on flat shores, the substratum of which is an irregular ex panse of stiff clay or other impervious formation. Pools of water are retained in the hollows, and become partially filled with sand or mud, which remains like the soft sediment in a cup of cocoa on ac count of the absence of drainage. The sand on a uniform shelving shore con solidates at low tide because the water which permeates it drains back freely to the sea. In narrow .thannels through which the configuration of the adjoining shore causes strong currents to run the sand may be kept so constantly stirred up by the moving water that a quicksand results. Thus, while the sum
mit of a sandbank rising from a gentle slope is usually firm, the hollow margin of the bank where it meets the shore is frequently a quicksand.
Quicksand, when examined under the microscope, will be seen to have rounded corners like river sand, as distinguished from angular or "sharp" sand, which will pack more solidly than the other. It is quicksand that is used in the hour glass and in the smaller egg-boiler.
Quicksands are not commonly of great extent, and their danger has probably been exaggerated in the popular mind by sensational descriptions in works of fiction. The name quicksand is some times applied to the drifting sands which are carried by wind over cultivated land bordering the seashore or a desert.