340 Prof. A. C. Ramsay on Geological Ages 



terrestrial origin, and both are clearly connected with long special con- 

 tinental epochs. 



Next come the various members of the Permian series, which, if my 

 published conclusions are correct, were partly formed in great inland 

 lakes, analogous to the Caspian Sea and other salt lakes of Central Asia 

 at the present day. Having been deposited in lakes, these subf orma- 

 tions may, in this one respect, be compared to the lacustrine strata of 

 Miocene age ; and if G-astaldi's conclusions with regard to part of the 

 Italian Miocene beds, and my own opinions respecting part of the 

 Permian strata, be correct, each series shows evidence of having included 

 a glacial episode. 



Later than the Permian comes the New Eed, or Triassic, series, which, 

 in this region, is not directly connected with the Permian strata, in so 

 far that, where they occur in contact, the New Bed Sandstone is gene- 

 rally unconformable to the Permian beds. In the threefold division of 

 the New Eed series in Prance and Germany, the marine beds of the 

 Muschelkalk (unknown in England) may be compared to the Lower or 

 Coralline Crag strata ; and, though the Keuper Marls of Britain and of 

 much of the Continent were evidently deposited in inland continental 

 salt lakes, in the region of the Alps the St. Cassian and Hallstadt 

 marine beds, being equivalent to the Keuper Marls, may in this respect 

 be compared to the Eed Crag series. No one is, I think, likely to con- 

 sider that the marine strata of Triassic age took a shorter time in their 

 deposition than the marine beds of the Crag ; and, if we take the New 

 Eed Sandstone into account, the probability is, that the whole of the 

 Triassic series occupied in their deposition a much longer time than that 

 taken in the deposition of the Pliocene marine strata. 



In my opinion, a great Tertiary continental phase began with the 

 Eocene strata; and that continent having undergone many physical 

 changes, has continued, down to the present day, with a certain amount 

 of identity ; and an analogous, though not strictly similar, state of things 

 prevailed for an older continent, during the deposition of a large part of 

 the formations treated of in this memoir. 



If the method founded on the foregoing comparisons be of value, we 

 then arrive at the general conclusion, that the great local continental era, 

 which began ivith the Old Red Sandstone and closed with the New Red 

 Marl, is comparable, in point of geological time, to that occupied in the 

 deposition of the whole of the Mesozoic, or Secondary, series, later than the 

 New Red Marl, and of all the Oainozoic, -or Tertiary, formations, and, 

 indeed, of all the time that has elapsed since the beginning of the deposi- 

 tion of the Lias down to the present day. To attempt to prove this 

 theorem is the special object of this paper ; and if I have been suc- 

 cessful, the corollary must be deduced that the modern continental 

 era which followed the oceanic submersion of a wide area, during which 

 the greater part of the Chalk was being deposited, has been of much 



