QUICKSANDS are those masses of loose or moving sand which are formed on many sea-coasta and generally at the mouths of rivers : those of the Nile and Senegal are among the most remarkable for these accumulations. The sands are generally conveyed by the rivers from the interior of the country, and being at first arrested by the waters of the ocean, they become, in many instances, by the action of the winds and tides, moveable bars, which are very dangerous to shipping. The loose mantle on the coasts aro, when dry, driven by winds over the land, which they then cover often to a considerable depth, overlaying the fertile ground and occasionally entombing whole villages : the coasts of Cornwall and Norfolk in England, and of Jutland in Denmark, are particularly subject to these encroachments [Dosss]; and it is stated that in the latter country there are vast beds of sand so loose as to be incapable of supporting the weight of a man. In Greenland there is a chain of leo-hills between two promontorts of moving sand, which is driven by the winds far out to sea.
The easterly movement which gives the character of quicksands to the arenaceous deposit» in and around the mouths of the Nile, takes place at all depths, and is extended to the shore itself. It is caused by the westerly gales and prevailing north-west breezes, which have also produced a range of sand-dunes extending from Cape Bottles at the most northerly point of Lake Boulos, eastward of the Rosetta branch of the river, to the mouth of the Damietta branch. These winds are both the accumulating and moving causes of this" stream of sand dunes," as it has been termed. As fast as the wind removes the sun-dried sand from the beach, the surf re-accumulates it again, during every gale. The quicksands, therefore, are littoral as well as marine phenomena. There is a constant movement of the sand in the deptha, both along the shore, and within the shore (which here merely separates the waters of the sea from those of the Delta), commencing from the ltoactta mouth on tho east, and extending to the Damietta mouth on the west It is also blown along the coast in a succession of dunes by one wind, or in part back again into the sea by another, less prevalent, but more violent wind. The subject is importantly connected with
that of one of the most remarkable projected enterprises of the present age, the " canalisation " of the Isthmus of Suez, in order to effect a navigable communication between the Mediterranean and the Red Sea. The subject has been treated by one of our !nest eminent marine sun-eying officers, Capt. Thomas A. B. Spratt, It.N., F.R.S., in An investigation of the Effect of the prevailing Wave influence on tlie N ilea Deposits, and upon the Littoral of its Delta,' dated Alexandria, July 9, 3858, printed with four lithographs of maps and sections, by the British Admiralty in the following year ;. and from which copious extracts have been made public in a parliamentary return of 1860. The preceding notice of the Niletic deposits has been derived from the original paper. Capt. Spratt's actual investigation was of the most practical nature, by the observation of the winds and sea-currents, the examination of the coast, that of the sea-bottom by dredging, and the mineralogical and chemical examination of the deposits. The result, broadly, is this, that the Mediterranean entrance to the proposed canal would be perpetually filled up by the moving sands of the Nile drifted by the sea along the coast, and that, in the attempt to construct and maintain it, millions of money would be fruitlessly lost in the depths of the sea.
The sand of Bag,shot Heath, which rests on the London clay, is in many places, at a few feet below the surface, saturated with water Be as to constitute a perfect quicksand : and, on the borders of Oman, in Arabia, there was discovered by Baron von Wrede a remarkable quick sand, which is said to be more than 60 feet deep.