300 THE EEGOLITH 



''The snrface of tlxe country composed of the more solid 

 forms of laterite is usually very barren, tlie trees and shrubs 

 growing upon it being thinly scattered and of small size. This 

 infertility is due, in great part, to the rock being so porous that 

 all the water sinks into it, and sufficient moisture is not retained 

 to support vegetation. The result is that laterite plateaux are 

 usually bare of soil, and frequently almost bare of vegetation. ' ' ^ 



"Waeke is an old German name now but little used, designating 

 the gray, brown to black earthy residue or clay resulting from 

 the decomposition in place of basic eruptive rocks, as basalt, 

 melaphyr, etc. In composition the material naturally varies 

 with the character of the rock from which it was derived, and 

 the amount of decomposition and leaching it may have undergone. 



It seems advisable to call attention here, a little more emphatic- 

 ally, to the fact that the same processes which in ages past have 

 been instrumental in the formation of sandstones, shales, slates, 

 or marls are to-day, and have in late Tertiary and in Quaternary 

 times, given us soils; in other words, many of our soils are but 

 secondary rocks in a state of loose consolidation, and many of 

 the accumulations classed as residual were derived by disintegra- 

 tion, in situ, of alluvial materials ; materials brought down years 

 ago and deposited in shallow seas. The amount of consolidation 

 undergone by the more recent of these sediments has in many 

 instances been so slight that on elevation above the water level 

 they are ready almost at once to assume the role of soil with little 

 if any preparatory disintegration. Nevertheless consistency de- 

 mands that such be here grouped as residuary. 



Over what is known as the coastal plain of the middle Atlan- 

 tic slope, a narrow belt bordering on the Atlantic and extending 

 from the Hudson Eiver on the north to the Roanoke on the 

 south, have been deposited in late Mesozoic and Tertiary times 

 a series of gravels, sands, and clays which constitute the well- 

 known Potomac, Appomattox, and Columbian formations of 

 Darton, McGee, and others. These are all detrital deposits 

 from the eastern Appalachian regions, brought down by streams 

 and deposited in the shallow estuaries and deltas of these 



^Manual of the Geology of India, by R. B. Oldliam, 2d ed., 1893, pp. 

 369-390. Max Bauer lias since shown (Neues Jahrb. fiir Min., etc., 1898, 

 Yol. II, p. 163) that the laterite of the Seychelles Islands in the Indian 

 Ocean, derived from granitic, syenitic and trappean rocks, is not properly 

 a ferruginous clay, but a mechanical admixture of free quartz, iron oxide 

 and alumina hydrate in the form of hydrargillite. 



