and its Influence on Climate. 439 



the sea-level. In short, we have evidence of a number of 

 oscillations of sea-level during post-Tertiary times*. 



Had there been but only one rise of the land relative to the 

 sea-level, or one depression, it might quite reasonably have 

 been attributed to an upheaval or a sinking of the ground, 

 occasioned by some volcanic, chemical, or other agency. But 

 certainly those repeated oscillations of sea-level, extending as 

 they do over so wide an area, look more like a rising and sink- 

 ing of the sea than of the land. But be this as it may, since it 

 is now established, I presume, beyond controversy that the old. 

 notion that the general level of the sea remains permanent, and 

 that the changes must be all attributed to the land, is wholly 

 incorrect, and that the sea, as well as the land, is subject to 

 changes of level, it is certainly quite a legitimate subject of 

 inquiry to consider whether the last elevation of the sea-level 

 relatively to the land may not have resulted from the rising of the 

 sea rather than from the sinking of the land — in short, 

 whether it may not be attributed to the cause we are now con- 

 sidering. The fact that those raised beaches and terraces are 

 found at so many different heights, and also so discontinuous, 

 along our coasts, might be urged as an objection to the opinion 

 that they were due to changes in the level of the sea itself. 

 Space will not permit of us entering upon the discussion of this 

 point at present ; but it may be stated that this objection is 

 more apparent than real. It by no means follows that beaches 

 of the same age must be at the same level. This has been 

 shown very clearly by Mr. W. Pengelly in a paper on " Raised 

 Beaches," read before the British Association at Nottingham 

 last year. 



We have, I presume, evidence amounting to almost absolute cer- 

 tainty that 11,700 years ago the general sea-level on the northern 

 hemisphere must have been higher than at present. And in 

 order to determine the question of the 25-feet beach, we 

 have merely to consider whether a rise to something like this 

 extent probably took place at the period in question. We have 

 at present no possible means of knowing with certainty the 

 extent of the rise which must have taken place at that period ; 

 for we have no means of ascertaining what was the quantity of 

 ice which must have then been melted off the antarctic regions. 

 But we have the means of making a very rough estimate, 

 which, at least, may enable us to determine whether a rise of 

 some 20 or 30 feet may not possibly have taken place. The 

 principal difficulty which meets us is the uncertainty that still 

 prevails regarding the amount of land within the antarctic 



* See Lyell's l Antiquity of Man,' second edition, p. 282 ; * Elements/ 

 sixth edition, p. 162. 



