1148. Earths of transportation is the term applied by Morton to those surface soils which are of a different nature to the rocks on which they rest. In some cases earths are washed down from mountains into valleys, and even on level land in great floods, earths may be taken up, and held in suspension by the water of a river which afterwards passes over a considerable extent of country carrying them with it, and thus they may become deposited on rocks quite different to those from which they were originally derived. Surface soils are also occasionally altered intentionally by the addition of other soils which contain qualities in which they are deficient; and it is in making these additions judiciously that the great art of culture consists.
