The theory of the subsequent infiltration of the gold is that generally accepted.
The remarkable " stone reefs " of the north-east coast are ancient beaches hardened by the infiltration of carbonate of lime.
Calcium oxalate is a very common substance, especially in crustaceous lichens; fatty oil in the form of drops or as an infiltration in the membrane is also common; it sometimes occurs in special cells and in extreme cases may represent 90% of the dry substance as in Verrucaria calciseda, Biatora immersa.
The recent investigations already referred to indicate the desirability of curving dams in plan in order to reduce the possibility of tension and infiltration of water at the upstream face.
Thus they are mainly responsible for the introduction of Islam with its Arabic or Persian civilization into India and Europe, and in earlier times their movements facilitated the infiltration of Graeco-Bactrian civilization into India, besides maintaining communication between China and the West.