THE GLACIAL PERIOD AND THE EARTH-MOVEMENT HYPOTHESIS. 251 



an elevation of 1,300 feet above the present level of the sea, and in 

 several other places at a lower level ; and those shells are certainly 

 referable to the inter-glacial stage. So that this one fact shows 

 that the earth's crust is capable, in comparatively recent periods 

 (speaking geologically of course), of undergoing considerable 

 alternations of elevation. I will not go farther into this topic 

 because I fear, if I did, I should occupy too long a time ; but I 

 should like to refer to one effect which the glacial epoch of the 

 Northern hemisphere had upon the regions which Professor Geikie 

 calls extra-glacial. He, in this Paper, has very clearly defined 

 what were the limits of these great ice sheets in Europe and 

 adjoining countries ; but the point I wish to refer to is to show 

 the effect which the glaciation of Northern Europe must have had 

 on the regions immediately to the south of the great ice sheets. 

 Now when travellers explore the central and northern parts of 

 Africa, Arabia Petrsea, the Great Arabian Desert and Palestine, 

 they are struck by the fact that those regions which are extra- 

 glacial, are traversed by magnificent valleys which were once, 

 undoubtedly, the channels of considerable rivers. Along the bot- 

 toms of those valleys we have alluvial strata in great terraces, 

 extending from side to side — perhaps two or three miles in width, 

 with well-defined banks on either side; yet those valleys are now 

 absolutely dry, or almost dry. The rivers are dispersed ; and we 

 ask ourselves — was there a time when these great river valleys, 

 which, for example, traverse the Sinaitic Peninsula and Southern 

 Palestine for many miles, were filled with streams ? No geologist 

 can hesitate as to the answer to that question. Every geologist 

 will say, at once, " Yes, there must have been rivers occupying 

 those channels." The interesting point connected with the sub- 

 ject is that we have to refer to this glacial period as affording us 

 an explanation of the mode of formation of these great river 

 valleys. We can quite understand that if the northern half of 

 Europe and the Lebanon were covered with perennial snows and 

 glaciers, the climate of the regions to the south of them would be 

 very different to what it is at present. They would, in fact, have 

 a climate similar to that of the British Islands at the present day. 

 Instead of being absolutely rainless, or nearly so, they would have 

 their proportionate rainfall, as is the case with our own country. 

 Therefore, we have in the glacial period a very interesting ex- 

 planation, as it seems to me, of the occurrence of these valleys 



