FORMATION OF SEDIMENTARY ROCKS 239 
and what is not precipitated remains in solution as part of the mineral 
matter of the sea. 
The following table shows the general plan of redistribution: 
TABLE I 
GENERAL PLAN OF REDISTRIBUTION 
Mechanical sediments (shales, 
Carried as solids | ORG Ges 
Material re- 
moved Chemical sediments  (lime- 
stones, etc.) 
Original Carried in solution Cementing materials 
Rock Vein-filling materials 
Mineral matter of the sea 
Weathered rock 
Material Te- eoecereeer ee eee ee ee ee © 
Residual clays or earth 
maining 
Various attempts have been made at quantitative estimates of 
the redistribution above outlined. Figures for the total thickness 
and relative amounts of the three classes of sediments have been 
obtained from actual measurement, but such estimates are confined 
to the present continental areas, taking no account of suboceanic 
deposits, and are limited to the comparatively small areas which 
have been studied by geologists. Several estimates have been made 
based on the nature and amount of material being carried to the sea 
by rivers, particularly on the ratio of calcareous to clastic sediments 
formed. 
A few estimates have been made based either in part or entirely 
on chemical evidence. One of these has been made by Van Hise,! 
who has determined the relative amounts of shale, sandstone, and 
limestone on the basis of observed thickness, combined with chemical 
considerations, to be 65 : 30: 5. Average chemical analyses of the 
shales, sandstones, and limestones were combined in the ratio of 
65 : 30: 5, respectively, and the resulting combination was found 
roughly to approximate the composition of the average crystalline 
rock. 
A more recent estimate of the same ratio is one made by Clarke,? 
based on chemical evidence. This estimate is discussed on a later page. 
tC. R. Van Hise, A Treatise on Metamor phism, Monograph No. 47, U.S. Geologi- 
cal Survey, 1904, chap. xi. 
2F. W. Clarke, ‘The Statistical Method in Chemical Geology,” Proceedings of 
the American Philosophical Society, Vol. XLV (1906), p. 21. 
