34 



consider the grounds on which the views in question were founded 

 yet he was not at all convinced that he was wrong in following- 

 Forbes. Mr. Stewart then gave a resume of the theory by which 

 the late Professor Edward Forbes accounted for the occurrence in 

 Ireland of an isolated group of plants that have their proper home 

 in the North- West of Europe. Forbes thought that these species 

 occupied this country prior to the glacial epoch, and that d \ring 

 the glacial period, which, was a period of cold and of sub- 

 sidence, they were cut off from what is now the Contine it of 

 Europe. On the c. r hand, Mr. Du Noyer has told us tiiat a 

 plain, connecting Spain with this country, existed after the glacial 

 era — in fact, that this plain was formed during that period by de- 

 position — and that when this sea-bottom emerged from the ocean 

 it formed a land surface, over which a migration of plants and 

 animals occurred. Further, Mr. Du Noyer thought subsidence 

 had nothing whatever to do with the isolation of Ireland from the 

 lands of North-West Europe ; but that work was done solely by 

 denudation — by the sea wearing away the land. But this view of 

 Mr. Du Noyer's gives much too vast an amount of work to be 

 done by the sea operating as it does now on these shores. The 

 time necessary for this work would be immense, even in the esti- 

 mation of a geologist ; for, remember, it is not only required that 

 the sea should wear away thousands of square miles of rock, but 

 also that the gentle flow of the Gulf Stream, and of Rennells' Cur- 

 rent, should scour out the bottom to its present depth. We all 

 must admit the power of the ocean waves, when they make their 

 tremendous impact on the rocky barrier that stops their career ; 

 but this power is exerted only between high and low tide levels : 

 all below is still and motionless, save the quiet flowing of the cur- 

 rents that everywhere maintain a circulation of the waters of the 

 great deep. The ship, when at the mercy of the waves that agitate 

 the surface, may be crushed like an egg shell ; but, once at the 

 bottom, she rests undisturbed, until, in the course of natural decay, 

 her disentegrated materials are dispersed. Either the sea-bottom 

 between the South- West of Ireland and the Spanish coast never 

 came to the surface after the glacial epoch ; or, if it did, there was 

 subsequent depression, by which, in conjunction with denudaiion 7 

 the isolation of this country was caused. 



