Dug aid Bell — The "Great Submergence." 63 



IV.— The " Great Submergence " Again : Clava, etc. Part II. 

 By DuGALD Bell, F.G.S. 



I AST month I glanced at some of the difficulties attaching to the 

 J theory of a " great submergence " during Glacial times, par- 

 ticularly in connection with the deposition of this shelly clay at 

 Clava. 



In regard to the alternative theory of transport by land-ice, the 

 following facts may be enumerated as so far in its favour : — 



(a) Evidences of ice-action are conspicuous all over the district. 

 It is a region of intense glaciation, and this special locality is right 

 in the tract of the ancient ice-sheet. 



(h) The traces of the movement show that, with a very small 

 submergence, the ice-sheet must have passed over part of a former 

 sea-bottom. 



(c) That in this neighbourhood it rose in its progress, carrying 

 numerous boulders with it in its course, and leaving them at higher 

 elevations than their parent beds of rock. 



These facts, we submit, give a -prima fade probability to the ice- 

 transport theory — to this extent at least, as showing that it does not 

 assume an agency or condition of things which cannot otherwise be 

 shown to have existed. The agency and conditions it assumes are 

 clearly made out to have been in force in the place and at the time, 

 and to have acted in the direction and on the scale, required. 



Has the submergence theory, on the other hand, any such in- 

 dependent evidence to support it ? Mr. Smith, for example, assumes 

 " deep, still water" at Clava, implying a total submergence of about 

 1000 feet ; and to this he adds " surface-currents carrying thin 

 shore-ice " laden with mud, stones, shells, etc. What is there to 

 support all these hypotheses ? Apart from the difficulty raised by 

 several eminent physicists as to the likelihood of there being any ice 

 at all in this country, with such a submergence, we ask where ai-e 

 there any traces of the assumed shore-line, at 1000 feet above the 

 present sea-level, from which the hypothetical " shore-ice " started ? 

 Are there no fragments of it among the hills of the district, or any- 

 where over the country ? Is the whole thing a series of suppositions 

 made to suit this particular case — resting on nothing — hanging, as 

 it were, in the clouds? At this rate, one can imagine anything — 

 even (as has been done) immense changes in the distribution of sea 

 and land, three or four tiu:ies repeated, to explain some purely local 

 phenomena ! 



Let us look now at some of Mr. Smith's objections to the theoiy 

 of the shells, or shelly clay, having been transported by land -ice, 

 merely premising that the many instances in which this theory is 

 undeniably true constitute a probability in favour of its being true in 

 this instance also. 



(1) So far as has been observed, there are no striations on the 

 shells ; and " it is physically impossible," says Mr. Smith, " that 

 the shelly clay with stones, or even the shells " could have been 

 transported by land-ice without being striated. They might, indeed. 



