4 02 EDWARD STEIDTMANN 



lands, is clearly shown by Becker 1 in his recent contribution, 

 "The Age of the Earth." 



Instead of leaving the composition of the lands as before, 

 redistribution might result in a selective withdrawal of certain 

 elements from the lands and possibly the retention of others. 

 This may be termed "selective" redistribution. Redistribution 

 has been selective with respect to sodium, resulting in a progressive 

 decline in the contribution of sodium from the lands to the sea. 

 It probably has been selective with respect to potassium, causing 

 only a slight accumulation of potassium in the sea as compared 

 with sodium. The question is raised here whether selective redis- 

 tribution may not have caused an actual progressive increase 

 in the calcium content of the lands and a correlative progressive 

 decrease in magnesium, which in turn may have been 'connected 

 with a similar progressive change in the ratio of calcium and mag- 

 nesium contributed to the sea, and of the calcium and magnesium 

 carbonates deposited in the sea. It has been pointed out that 

 regardless of whether the primary lithosphere was rhyolite or 

 basalt, redistribution would result in a large proportion of elas- 

 tics, predominantly mud, and a small proportion of limestone. If 

 redistribution has been integral with respect to elastics and lime- 

 stones, it would follow that the sediments exposed on the conti- 

 nents are predominantly elastics and subordinately limestones. 

 This test will be applied here to the continental interiors, the 

 continental margins, the epicontinental seas and the deep seas, 

 so far as the progress of my studies permits. 



The geologic record of the continental interiors. — The greater 

 portion of the surface of the lands consists of sediments. Major 

 Tillo 2 estimates that the Archaean and younger eruptives constitute 

 only 24. 3 per cent of the known area of the continents. It follows 

 from obvious reasons that the greater part of the calcium and 

 magnesium now being delivered to the sea by the rivers comes 

 from the sediments exposed on the lands, and the proportions of 

 calcium and magnesium in the rivers will be roughly proportional 



1 G. F. Becker, "The Age of the Earth," Smithsonian Inst. Miscellaneous Collec- 

 tions, LVT (1910), No. 6. 



2 Quoted from Berghaus' Atlas der Geologic (1892). 



