A Geological Retrospect of the Year \^^2. 195 



■of vegetation. He thonglit that this organic deposit increased in 

 thickness at the rate of one foot in a century, so that in no long 

 -course of time it must deeply bury the old sea-floor and even cover 

 np the ridges of deposited granite. He did not show, however, by 

 what means this general elevation of the surface of the plain could 

 possibly be accomplished in face of the universal degradation caused 

 by atmospheric decay and the circulation of water over the land — 

 a destructive combination which he had already admitted that 

 nothing can resist. Nor did he offer any explanation of the cause of 

 the ultimate cessation of the upward growth of the organic deposit, 

 or why after burying the granite ridges it eventually i'ailed to keep 

 pace with the erosive action of rain and rivers. Without noticing 

 such obvious and serious objections to his theories, he could only 

 •contemplate the final result of the long process of earth-sculpture — 

 tlie trenching of the terrestrial plain by running water, into gullies, 

 gorges, and valleys, and at last the uncovering of the hard central 

 cores of granite now to be seen in the heart of so many mountain- 

 chains (pp. 149, 178). 



It was when he left such speculations as these, for which no 

 adequate basis of ascertained fact then existed, and turned bis 

 consummate genius to the patient study of the organic remains 

 imbedded in the earth's crust, that Lamarck conferred the most 

 valuable and imperishable benefits on the infant science of geology. 

 The word ' fossil ' had up to his time been indiscriminately applied 

 to any substance dug out of the ground. Every mineral and rock 

 was in this sense a fossil. But Lamarck, recognising the pre- 

 eminent importance of organic remains as monuments of the history 

 of the glol3e, first restricted the use of the word to them alone, 

 and his example has since been everywhere followed. In the 

 " Hydrogeologie " he pointed out that as fossil shells are nearly all 

 of marine types their evidence could be used to demonstrate that the 

 sea once covered the site of what is now land, and this by no mere 

 transient and violent inundation, but tranquilly and for vast periods 

 of time. As Lavoisier had done before him, he distinguished among 

 tliem some that belonged to littoral or shallow-water species and 

 others that were deep-sea or pelagic forms. He entered into 

 a lengthened argument to disprove what had been for so many 

 generations the orthodox belief that the shells found far inland and 

 in the heart of mountains are memorials of Noah's Flood. Dwelling 

 on the manner in which pelagic and littoral shells are found in 

 separate beds, piled above each other, he insisted on the evidence 

 thus furnished of successive quiet and long-continued deposition on 

 the sea-bottom. He pointed to the significant occurrence of the two 

 valves of bivalve shells still adhering to each other as proof that 

 these organisms, instead of having been violently huddled together 

 by some great catastrophe, had manifestly lived and died where 

 their remains are now found. When he considered the abundance 

 of marine organisms in our present seas and the vast amount of 

 carbonate of lime secreted by them from the oceanic waters, he felt 

 ■convinced that the masses of limestone which form so important 



