20 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



the Chalk, and its freedom from any quantity of terrigenous 

 sediment can best be explained (in view of the fact that it 

 contains shallow- water forms of life, and was bordered by 

 land as close as N.W. Scotland and Ireland, the Harz Mountains, 

 Scandinavia, and a belt which separated it in part from the 

 Hippurite-sea, of Southern France, the Alps, and Central 

 Europe) by postulating a relatively low level and condition of 

 peneplanation of the land, and distance from large rivers 

 bringing terrigenous sediment. 



Not only may gentle movements leave their mark upon 

 the rocks, but earthquakes yield records which have of late 

 been recognized more widely in ancient sediments than hitherto. 

 Professor P. F. Kendall has adduced evidence of earthquake 

 disturbances during the Coal Measure Period, many of the 

 features of present-day earthquakes, such as rifts, fissures, 

 undulations, ridges, hollows, pipes, " sand-blows," and over- 

 riding having been found.* Similarly, the marvellous accumu- 

 lation in the Old Ked Sandstone of the distorted remains of 

 innumerable fish may be evidence of earthquake shocks, 

 submarine or terrestrial, such as those that to-day kill off large 

 quantities of fish, the bodies of which are found floating on the 

 surface. The Old Red Sandstone was deposited during a 

 period renowned for its mountain-building movements with 

 accompanying volcanic outbursts. Sir A. Geikie has suggested 

 that mephitic vapours poured out by the volcanoes were the 

 cause of the high death-rate and the large accumulation of 

 fish remains. 



(7) The existence of other classes of organisms. Often it is 

 possible to adduce from the strata evidence as to the conditions 

 of food-supply, the struggle for existence, and the reasons for 

 the survival of certain families of organisms. Thus, the 

 supposition as to a relationship between the decline of the 

 trilobites, and the rise of the ganoid fishes, receives strong 

 * Proc. Geol. 8oc, No. 1031, (1919), p. 28. 



