FORMATION OF SEDIMENTARY ROCKS 251 
resulting end-products. As would be expected, the ratio obtained 
from the average crystalline rock lies between those obtained for 
acid and for basic rocks; but it is noticed that the intermediate figure, 80 
per cent., lies nearer the percentage of shale derived from acid rocks, 
79 per cent., than that derived from basic rocks, 88 per cent. This 
indicates that in the group of analyses from which Clarke’s average 
crystalline rock was obtained there was a considerable predominance 
of acid rock over basic rocks. This is in accord with the general 
opinion as to their relative importance. 
DISCREPANCIES 
In the following table the analyses of shales, sandstone, and lime- 
stone given in Table III have been combined in the ratios of 82:12:6, 
respectively, derived elements only being considered, and the resulting 
combination compared with the average crystalline rock. 
TABLE IV 
Average Analyses of Differences between the 
Composition of Av- Shales, Sandstone, ee 
creer Crystalline and mesons com- oe ona R et ae 
oc bined in the ratios of = F 
82:12:6 respectively Comb. of Sediments 
STO perce nay hae antes 61.60 63.64 +2.04 
PAN @ i Misirats saeien eoewe aye 15 A nals fat —O170 
Ie wcuiecaye Misnensioiar tuscan yee 4.60 4.46 —0.13 
IMO) Ain Geile Aah IAG ot 4.18 2.90 —1.28 
(Cal OP Me aoe iarhencastpoiese 4-93 7.34 sa epoalae 
IN eas Oise ant sesrcietietanel as tay 3.50 1.29 eH 
IO a coal Pree pecan tec penne 3.02 Beaty) areaake) 
In the right-hand column the plus signs indicate an excess of that 
element in the sediments, and a minus sign indicates a deficiency. 
While the sedimentary rocks form a very large proportion of the 
end-products of redistribution, it is evident that in considering only 
the sediments, as has been done in the solution of this problem, certain 
discrepancies may arise owing to the omission of the other end- 
products. These omitted end-products may account to a consider- 
able extent for the discrepancies in Table IV. The most important 
of these omitted factors which admit at all of quantitative considera- 
tion are: mineral matter of the sea, the iron formations, and the 
residuary matter of the land. With a view of ascertaining to what 
extent the omission of these factors is responsible for the discrepancies 
