ANNIYEESAKY ADDRESS OP THE PRESIDENT. 6$ 



the Lower Old Eed Sandstone was deposited. Even now we can 

 trace some of their shore-lines, walk over the shingle of their 

 beaches, examine the silt of their deeper gulfs, and exhume the 

 remains of the plants that shaded their borders, as well as of the 

 fishes that swarmed in their waters. The sediments which accu- 

 mulated in some of these basins amount to many thousand feet in 

 thickness ; yet from bottom to top they abound in evidence of 

 shallow-water conditions of deposit. We are thus led to infer that 

 the disturbance of the crust which brought about the formation of the 

 hollows continued for a vast interval, the .floors of the basins sinking 

 and the intervening tracts being ridged up as the results of one 

 great movement of the terrestrial crust, while at the same time the 

 surface of the land was undergoing extensive denudation and the 

 basins were receiving a constant influx of sediment. 



We need not suppose that these movements of subsidence and 

 upheaval were uninterrupted and uniform. Indeed, the abundant 

 coarse conglomerates which play so prominent a part in the mate- 

 rials thrown into the basins serve to suggest that at various intervals 

 during the prolonged sedimentation the subterranean disturbances 

 were specially vigorous. But the occurrence of strong unconforma- 

 bilities among the deposits of the basins sets this question at rest by 

 proving that the terrestrial movements were so great as to break up 

 the floor of one of the largest of the lakes and to place its older 

 sediments on end, in which position they were covered up and 

 deeply buried by the succeeding deposits. 



Among the many points of interest in the Old Eed Sandstone of 

 this country, not the least impressive is the evidence that the 

 terrestrial disturbances to which I have alluded were accompanied 

 and followed by prolonged and vigorous volcanic action. Groups of 

 volcanoes rose in long lines from the waters of most of the lakes, 

 and threw out enormous quantities of lava and ashes over tracts 

 hundreds of square miles in extent. So vast indeed were these 

 discharges across what is now the Midland Yalley of Scotland that 

 the portions of sheets of lava and tuff visible at the surface form 

 some of the most conspicuous ranges of hills in that district, stretch- 

 ing continuously for forty or fifty miles and reaching heights of 

 more than 2000 feet above the sea. Exposed in hundreds of 

 ravines and escarpments, and dissected by the waves along both the 

 eastern and western coasts of the country, these volcanic records 

 may be studied with a fulness of detail which cannot be found 

 among earlier Palaeozoic formations. 



