250 THE CHAIN OF LIFE. ■ 



has well remarked, the actual configuration of our continents, 

 the amount of drift still remaining, and the imperfect manner 

 in which the river valleys have been cleared out, all testify to 

 the comparative recency of the Glacial period. ^ These con- 

 siderations would, indeed, materially reduce the antiquity 

 which he claims on astronomical grounds for the ice age. 



(4) The growth of peat and the deposition of silt are very 

 deceptive as indications of great antiquity. For instance, 

 accurate observations made by a French engineer in the con- 

 struction of docks at St. Nazaire,^ show that in 1600 years the 

 Loire had deposited over Gallo-Roman rem.ains six metres of 

 mud. Relics of the Bronze age occur below these at a depth 

 indicating 500 years previously as their date ; and the beginning 

 of the modern deposit of the Loire would, on the same evidence, 

 be only 6000 years ago. Hilgard's observations on the delta of 

 the Mississippi in like manner tend greatly to reduce our esti- 

 mates of the time o upied in the deposit of the modern silt of 

 that river. The peat deposit at Abbeville, at the mouth of the 

 Somme, has been supposed to be a deposit requiring 30,000 

 years for its formation. But this estimate was based upon the 

 present rate of deposit ; and, as Andrews has shown, the fact 

 admitted by Boucher de Perthes, that birch stems three feet 

 high stand in this peat, implies a much more rapid deposit, 

 which is also proved by the depth at which Roman remains 

 have been found. In like manner the Scandinavian peats, to 

 which a fabulous antiquity has been ascribed, have been proved 

 to be comparatively modern by the depths at which metallic 

 works of art are found in them. 



(5) The paucity of remains of Paloeocosmic men in Europe, 

 with their wide distribution, indicate that their sojourn was not 

 long, or that the population was very small and much scattered. 

 Even in a few thousands of years, an active and vigorous 



1 Climate and Time, a work in which these and other matters relating to 

 the Glacial period are very well discussed. 



2 Kimber, quoted by Southall. 



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