Alluvium

Collier's New Encyclopedia (1921)

the act or process of washing away soil, gravel, rocks, etc., and depositing the débris in other places; also, the materials thus deposited. In geology the form of the word is alluvium, or, rarely, alluvion. Alluvium is especially employed to designate the transported matter laid down by fresh water during the Pleistocene and recent periods. The most typical example of alluvium may be seen in the deltas of the Nile, Ganges, Mississippi, and many other rivers. Some rivers have alluviums of different ages on the slopes down into their valleys. The more modern of these belong to the recent period, as do the organic and other remains which they contain, while the older (as those of the Somme, Thames, Ouse, etc.), which are of the Pleistocene age, inclose more or less rudely chipped flint implements, with the remains of mammals either locally or everywhere extinct. Volcanic alluvium is sand, ashes, etc., which, after being emitted from a vol cano, come under the action of water, and are by it redeposited, as was the case with the materials which entered and filled the interior of houses of Pompeii. Marine alluvium is alluvium produced by inundations of the sea, such as those which have from time to time overflowed the eastern coast of India. In English law, the form of the word generally used is alluvion, and in Scotch law alluvio. In both of these the enactment is, that if an "eyott," or little island, arise in a river midway between the two banks, it belongs in common to the proprietors on the opposite banks; but if it arise nearer one side, then it belongs to the proprietor whose land it there adjoins.