Vol. 60.] ANNIVERSARY ADDRESS. IxXXlii 



of philosophic analysis, who has himself looked at some of 

 the evidence on the ground, and has diligently perused the litera- 

 ture of the subject, they deserve the most serious consideration. 

 It may serve some useful purpose, therefore, if we pass in brief 

 review the state of the evidence presented in our islands for the 

 discussion of this disputed problem. 



Xo features in British geology are more familiar than the 

 abundant proofs which have been brought forward of comparatively- 

 recent changes of level, both in an upward and downward direction. 

 A somewhat complex series of oscillations has been recognized, re- 

 garding the true amount and sequence of which opinions are still 

 divided. It is no part of my present purpose, however, to review 

 the whole length and breadth of this complicated piece of geological 

 history. I will not enter upon the consideration of the sequence 

 •of the successive oscillations of which the records remain more or 

 less clearly preserved. For the discussion which I propose it will 

 be sufficient to consider the character of the evidence that will best 

 furnish answers to the two questions : 1st. What reliable proofs 

 can be adduced of Pleistocene and post-Pleistocene changes in the 

 relative levels of land and sea ? ; and, 2ndly. How far do these proofs 

 carry us in the endeavour to ascertain whether the changes have 

 resulted from oscillation of the sea-level, or from movements of the 

 solid land ? 



In all such discussions it is difficult to avoid the use of a long- 

 established terminology, which has been generally accepted as cor- 

 rectly expressive of the facts to which it is applied. We have been 

 accustomed to speak of the movements as inherent in the land rather 

 than in the sea. But it may be desirable, in our examination of the 

 facts, to avoid the use of such terms as Elevation or Upheaval, and 

 Depression or Subsidence, as too obviously begging the question 

 to be answered. Instead of using^these phrases I will speak of the 

 Emergence and Submergence of Land, the former being the 

 negative and the latter the positive movements of Prof. Suess's 

 nomenclature. 



I. Evidence for the Emergence and Submergence of Land. 



» 



(i) Emergence. 



Various kinds of evidence have long been cited by geologists, 

 in proof that what is now dry land has once been under the sea. 

 The favourite demonstration has been based on the presence of 



