James Croll — On the Glacial Epoch. 349, 



would be a succession of cold and warm periods, and consequently 

 a succession of elevations and depressions of sea-level. And the 

 elevations of the sea-level would take place during the cold periods, 

 and the depressions during the warm periods. 



But the agreement between theory and observed facts does not 

 terminate here. It follows from theory that the greatest oscillations 

 of sea-level would take place during the severest part of the Glacial 

 epoch, when the eccentricity of the earth's orbit would be at its 

 highest value, and that the oscillations would gradually diminish 

 in extent as the eccentricity diminished and the climate gradually 

 became less severe. Now it is well known that this is actually 

 what took place ; the great submergence, as well as the great 

 elevation or continental period, occurred during the earlier or more 

 severe part of the Glacial epoch, and as the climate grew less severe 

 these changes became of less extent, till we find them terminating in 

 our submerged forests and 25-foot raised beach. 



It follows therefore, according to the theory advanced, that the 

 mere fact of an area having been under sea does not imply that 

 there has been any subsidence or elevation of the land, and that 

 consequently the inference which has been drawn from these sub- 

 merged areas as to changes in physical geography may be in many 

 cases not well founded. 



Sir Charles Lyell, in his " Principles," publishes a map showing 

 the extent of surface in Europe which has been covered by the sea 

 since the earlier part of the Tertiary period. This map is intended 

 to show the extraordinary amount of subsidence and elevation of the 

 land which has taken place during that period. It is necessary for 

 Sir Charles's theory of the cause of the Glacial epoch that changes in 

 the physical geography of the globe to an enormous extent should 

 have taken place during a very recent period, in order to account for 

 the great change of climate which occurred at that epoch. But if 

 the foregoing results be anything like correct, it does not necessarily 

 follow that there must have been great changes in the physical 

 geography of Europe, simply because the sea covered those areas 

 marked in the map, for this may have been produced by oscillations 

 of sea-level, and not by changes in the land. In fact, the areas 

 marked in Sir Charles's map as having been covered by the sea, are 

 just those which would be covered were the sea-level raised a few 

 hundred feet. No doubt there were elevations and subsidences in 

 many of the areas marked in the map during the Tertiary period, 

 and to this cause a considerable amount of the submergence might 

 be due ; but I have little doubt that by far the greater part must be 

 attributed to oscillations of sea-level. It is no objection that the 

 greater part of the shells and other organic remains found in the 

 marine deposits of those areas are not indicative of a cold or glacial 

 condition of climate, for, as we have seen, the greatest submergence 

 would probably have taken place either before the more severe cold 

 had set in or after it had to a great extent passed away. That the 

 submergence of those areas probably resulted from elevations of 

 sea-level rather than depressions of the land, is further evident from 



