MATERIAL OF THE SEDIMENTARY ROCKS. 559 



ROCKS PRODUCED FROM MATERIAL OF BELT OF WEATHERING WITHOUT 

 TRANSPORTATION TO THE SEA. 



While by far the larger part of the material produced by the processes 

 of weathering is transported to the sea, either in suspension or solution, the 

 weathered material may be buried under other deposits without transpor- 

 tation to the sea. The weathered material not carried to the ocean may 

 be classified into residuary and transported material. Such deposits may 

 be from a few meters to hundreds of meters, or, in the case of the trans- 

 ported material, even a thousand meters in thickness. After a deposit of 

 residuary or transported material has accumulated, the sea may transgress 

 over the region so quietly as not to disturb the larger part of the weathered 

 rock. As an example of the burial of residuary material under marine 

 deposits may be mentioned the Coastal Plain of the United States. Here 

 the deeply disintegrated pre-Cretaceous rocks have been overridden by the 

 ocean, and upon them have been laid down the Coastal Plain deposits. If 

 the sea should now advance over the Piedmont Plateau somewhat rapidly 

 part of the deeply disintegrated and decomposed belt there occurring might 

 be buried under marine deposits without disturbance. 



Weathered material may be transported a greater or less distance, but 

 not to the sea, and thick deposits be built up. This is well illustrated by 

 the deposits of the Great Basin region of the United States. Here the 

 weathered material, instead of being transported to the sea, continuously 

 accumulates in the lower areas. This has gone on until there are hun- 

 dreds or a thousand or more meters of weathered rock material, which has 

 accumulated between the mountains. Some of this material is deposited 

 by the streams; other parts are deposited by the ephemeral lakes; others 

 by the permanent lakes. (See pp. 551-554.) The result is the building of 

 great sedimentary deposits, in which there is local assorting. When the sea 

 next encroaches upon this Great Basin area there may be buried below 

 the marine deposits a great mass of weathered material, which differs 

 radically from the ordinary marine deposits in that there has been com- 

 parativelv little abstraction of soluble salts, and which therefore must have 

 nearly the same average chemical composition as the original rocks from 

 which they are derived, but not the same mineral composition. 



The residuary or transported material, when sufficiently deeply buried, 

 whether below the sea or by upbuilding, as in the Great Basin area, passes 



