1865.] JAMIESON — ^LAST CHANGES IN SCOTLAND. 173 



surface of the Loch of Monteith, as I learn from the Ordnance 

 Survey, is only 55 feet above the present mean level of the sea. A 

 submergence, therefore, that would account for the marine strata of 

 Gartness, would, in the present configuration of the country, cover 

 the site of this little lake, as well as the greater part of these 

 mounds. 



Does it not, therefore, look as if the glacier had occupied the 

 vaUey of the Forth, at least as far down as this little lake, after the 

 marine beds were deposited on the higher grounds ? 



Part of the lake is said to be very deep ; the bottom, therefore, is 

 probably in some places lower than the present sea-level, seeing that 

 the surface is only 55 feet above it. 



The eastern base of the mounds meets the upper extremity of the 

 " Carse " of Stirling, which is a flat expanse of fine alluvial soil, 

 covered here and there with peat. The surface of this Carse is only 

 30 feet or so above the sea ; it encircles these moraine-Hke heaps, 

 and seems to overlap their base, as if it had been gently deposited 

 around them long after their formation. 



b. Character of the Fossils. — The MoUusca, whose remains are 

 found in the glacial beds of Scotland, are of a much more northern 

 character than the group which inhabits the seas of Britain at the 

 present day. This result was clearly brought out by Mr. Smith of 

 Jordan Hill many years ago ; and aU subsequent investigation has 

 tended to confirm the accuracy of his induction. In the clays and 

 sands of the east of Scotland the shells are much rarer, and in worse 

 preservation, than they are in the Clyde beds. 



Some of the shelly clays of the Clyde district and of the west coast 

 seem to belong to the close of the submergence, when the land had 

 risen well out of the sea, almost to its present height. This is well 

 exemplified at the Kilchattan brickwork in the island of Bute, where 

 we have at the bottom a thick mass of laminated clay destitute of 

 shells, and lying upon an irregular surface of the boulder-earth, 

 which, again, is found at the distance of 70 yards to repose upon the 

 Devonian rocks, or Old Red Sandstone (see section, fig. 4). The 

 surface of this fine laminated brick-clay is undulated ; and resting 

 upon the top of it, so as to fiU up the undulations and bring 

 the surface to a nearly horizontal plane, we find a looser, sandier 

 clay full of shells. Of these I collected sixteen species (see Ap- 

 pendix, No. 3). The most common is the Tellina calcarea (T. 

 proxima of Brown). It is very abundant, and of all sizes, from 

 1 inch in length down to very young individuals ; and they are 

 often quite entire, as if there had been a bed of them in situ. 

 This loose sandy stratum varies in thickness from a few inches, 

 or almost nothing on the top of the undulating rolls of the lower 

 clay, to 3 feet or more in the hollows. Where there is much 

 depth of it, the sjiells are chiefly in the lower part. Above this 

 shelly stratum we find a heavy mass of stratified gravel and shingle 

 from 4 to 10 feet thick, looking as if it had been formed on a beach. 

 Here, then, we have, subsequent to the Boulder-clay, three changes 

 of conditions in the marine beds : first and lowest, we have the 



