1865.] JAMIESON LAST CHANGES IN SCOTLAND; 189 



I also observed shells (Scrohicularia pi^erata) in the same clay at 

 Stirling ; and at Polgavie on the Tay a bed of similar shells occurs 

 in the raised estuarine mud overlying the peat-bed with trees. 



Three or four instances have occurred of remains of the Whale in 

 this Carse-clay of the Forth, namely at Dunmore, Airthrey, Blair- 

 Drummond, and Micklewood. Those at Airthrey and Dunmore* 

 were entire skeletons about 70 feet long, and were imbedded 

 in the clay at a height of fully 20 feet above the present reach 

 of the tidef. The depth of this old estuarine mud is in some places 

 very great, more especially below Stirling, where Mr. Blackadder 

 says a depth of 70 feet has been reached ; and Mr. Bald in- 

 forms us that near Alloa there is 90 feet of it, A mass of such 

 extent and thickness must have required a long time for its accu- 

 mulation. This clay is generally stiffest and contains least sand 

 near the surface, so much so as to be frequently employed for making 

 bricks and tiles. There are works of this nature at Stirling, Mickle- 

 wood, Inchture, Perth, and elsewhere in the Carse ; accordingly 

 some people have confounded it with the older glacial clay, which is 

 the stuff generally employed in Scotland for manufacturing bricks, 

 tiles, and wares of that sort, although some of the beds of the Coal- 

 measures are likewise used. 



The fact of the Carse-clay extending up the Forth as far as Gart- 

 more (see Mr. Blackadder's map), which is only ten miles from Ben 

 Lomond and six from Ben Yenne, and, fringing as with a smooth 

 carpet the base of the moraine-hillocks of the Loch of Monteith, 

 shows that it has been postglacial, and has never been disturbed by 

 the ice. There is a remarkable absence of stones in it, even of the 

 smallest pebbles. 



The raised estuarine beds may be traced along the coast at various 

 places, as at the Montrose basin, Aberdeen, and the mouth of the 

 River Ythan, everywhere containing the same group of shells. The 

 Scrobicularia inperata may be said to be characteristic of these beds ; 

 for it is not found in the glacial clays, and seems to have died out 

 along the east coast of Scotland in many places where it was formerly 

 abundant. In a fossil state it is plentiful in the raised estuarine mud 

 of the Ythan, and also at Aberdeen, Montrose, and the Loch of 

 Spynie, near Elgin, as well as in the Carse of the Forth. Mr. Gwyn 

 Jeffi-'eys tells me that it is not uncommon alive on the west coast of 

 Scotland, and that it lives in the estuary of the Gotha, and other 

 places on the coast of Sweden; its range, however, is essentially 

 southward. 



In tracing the distribution of these old estuarine deposits along the 

 east coast of Scotland, I have remarked that their elevation becomes 

 less as we proceed from the Fii'th of Forth to Aberdeenshire. In 

 the basin of the Forth the Carse-clay lines the side of the vaUey to 

 the height of 25 or 30 feet above the present sea-level. The old 

 estuarine mud of the Tay reaches to about the same height. At the 



* Edinb. Phil. Journ. vol. xi. p. 220 (1824). 



t Edinb. Phil. Journ. vol. i. p. 393, where there is a good account of the 

 finding of the Airthrey Whale by Mr. Bald (1819). 



