Pallas 83 



The primitive schistose band of the great chains is 

 immediately succeeded by the calcareous band, which 

 consists first of solid masses of limestone, either containing 

 no marine productions or only slight traces of them. The 

 thick beds of limestone are placed at high angles and 

 parallel to the direction of the chain, which is also gener- 

 ally that of the schistose band. As they recede from the 

 line of the mountains, the limestones rapidly sink down 

 into a horizontal position, and soon appear full of shells, 

 corals and other marine organisms. These upheaved lime- 

 stones form his Secondary mountains. A third series of 

 rocks, which seemed to him to be the record of some of 

 the latest revolutions of the globe, consists of sandstones, 

 marls, and various other strata, forming a chain of lower 

 hills in front of the limestone range. To this series of 

 deposits he gave the name of Tertiary mountains. 



These geological terms, thus proposed by Pallas, were 

 not of course used by him in their more precise modem 

 definition. We know, for example, that his Tertiary 

 mountains consisted mainly of the younger Palaeozoic 

 sediments which are now called Permian, and that with 

 these ancient formations he included the sands and clays 

 that inclose the remains of mammoth, rhinoceros and 

 other extinct mammals. 



The main value of his observations lies in his clear 

 recognition of a geological sequence in passing from the 

 centre to the outside of a mountain-chain. He saw that 

 the oldest portions were to be found along the axis of the 

 chain, and the youngest on the lower grounds on either 

 side. He recognized also that the sea had left abundant 

 proofs of its former presence on the land, he thought that 



