76 Introduction to Geology, 



destroyed many races of animals, particularly the larger car- 

 nivorous quadrupeds, that then inhabited the land, and even 

 some inhabitants of the waters, if we judge from the extinct 

 species which we trace in this debacle. 



It has been stated, that there appears ample evidence of the 

 frequent occurrence of similar catastrophes, the consequence 

 of inundations more or less extensive. That to which we now 

 refer was, therefore, the last of these revolutions, and modi- 

 fied the form of the land as we now view it. Geologists are 

 agreed in designating the mass of transported materials, re- 

 sulting from that event, by the term diluvial. 



Few deposits are so interesting to the naturalist. It contains 

 not only the remains of those organic beings which then 

 peopled the earth, and acquaints us with the zoology of that 

 remote period, but it comprises portions derived from many 

 older formations, and, on tracing these fragments to their 

 original sites, enables us even to perceive the direction of this 

 diluvial current. 



Remains of mammiferous animals have been discovered in 

 most of the great diluvial valleys in England ; nor are they 

 confined to these low sites, but have often been found em- 

 bedded in the gravel of our hills. 



How far all deposits of this character may be affirmed to 

 be absolutely contemporaneous must remain unsettled for a 

 time. It can only be decided ultimately by the physical evi- 

 dence that can be brought to bear upon the question. In the 

 present state of our knowledge, there seems no reason to reject 

 the distinction originally made by Dr. Buckland, between the 

 detritus formed by the Mosaic deluge, and those deposits 

 which accumulate from causes now in action. With respect 

 to the thickness of diluvial matter, its greatest accumulation is 

 probably on the coast of Norfolk where it is more than 250 ft. 

 in thickness. Our sections (figs. 123. and 124.) represent 

 portions of the cliffs of that county. Mr. De la Beche observed 

 in Jamaica, that the diluvial gravel was from 200 to 300 ft. 

 thick. In some parts of Switzerland, it is stated to he more 

 than 600 ft. in depth . 



An investigation of these deposits will contribute much to 

 our knowledge of the force and direction of diluvial currents. 

 Mr. Farey long ago remarked, that no true theory of the 

 earth or system of geology will ever be produced, which does 

 not embrace a knowledge of diluvial ground equally or more 

 intimate than that of " all the primitive and transition coun- 

 tries in the world; because, diluvium being vastly inore spread 

 indicates later operations on our planet, and is more within the 

 reach of our investigations than the formation of mountains." 



