XC TKOCEEDIXGS OF THE GEOLOGICAL SOCIETY. [May I904, 



sides of the island at corresponding heights. No possible arrange- 

 ment of ice-dams in the Atlantic and in the basin of the North Sea 

 •can be conceived that would have everywhere ponded bock the 

 land-drainage to similar levels. (2) Their independence of local 

 conditions. The same terrace may be traced down both sides of 

 a sea-loch and round the coast into the next loch, retaining all 

 the while its horizontal continuity. Not only on the mainland, 

 but on the chain of islands outside, the same parallel bar has 

 been incised, both on the inner or sheltered side and also on the 

 outer flank looking to the open Atlantic. (3) Their organic 

 remains. From the youngest of the beaches up to the highest, the 

 terraces of deposit contain marine organisms which have not been 

 scooped out of some earlier formation, but lie in the positions in 

 which the animals died, or into which they were washed by shore- 

 waves and currents. The fossils of the latest beaches are entirely 

 identical, or almost so. with forms still living in the adjacent seas, 

 while those of the higher beaches are boreal or Arctic. 



In some sheltered places, such as the Dornoch Firth, especially 

 near Tain, and some inlets on the west side of the island of Jura, 

 a number of successive bars or terraces of deposit may be observed, 

 up to heights of 100 feet or -more above the sea. But there are 

 in Scotland three strand-lines so conspicuous and so persistent that 

 attention may be confined to them. From what has been taken 

 to be their average height above mean sea-level or Ordnance-datum, 

 they are known respectively as the 100-foot, the 50-foot, and the 

 25-foot beaches. 



Here I should like to point out what I have long regarded as a 

 reproach to the geologists of this country. No systematic effort 

 has ever yet been made to determine accuratelv, bv a series of 

 careful levellings, the precise heights of these old shore-lines. We 

 only know that, roughly speaking, a raised beach retains its level 

 for long distances, and appears to lie at the same height on both 

 sides of the country. But we are still ignorant whether or not an 

 appreciable difference of level might not be detected between the 

 western and the eastern development of the same beach, nor do we 

 know whether it would not betray some variation in its height 

 between its northern and southern limits. There seems to be a 

 tendency for the levels of the beaches to rise slightly towards the 

 head of an estuary or sea-loch. But whether this difference is more 

 than can be accounted for by the ordinary elevation of the tidal 

 wave as it ascends a narrowing inlet, remains to be determined. 



