BRITISH POSTGLACIAL & RECENT DEPOSITS 395 



These, however, appear to be restricted to the lower reaches of 

 the Carse of Gowrie. Thus Mr. Jamieson mentions the occur- 

 rence of Scrdbicularia pijperata in the silt and clay which overlie 

 the old buried forest at Polgavie ; and I have seen quantities of 

 the same shell turned up during the digging of a deep drain in 

 the Carse near Inchture. But I have not observed any marine 

 organic remains in the Carse-clays farther up the valley, 1 al- 

 though there appears no reason why sea-shells should not occur 

 now and then as far up the valley at least as Glencarse. There 

 are, however, comparatively few good exposures, and the shells, 

 for various reasons, were probably never very abundantly distri- 

 buted through the deposits. When they do occur, it is usually 

 in thin, lenticular beds, which seem to be quite local, so that, 

 in the absence of deep cuttings and continuous sections, our 

 chances of coming upon such isolated patches are small. 



I have mentioned the fact that when the Carse-clays are 

 followed up the valleys, they eventually pass into true river- 

 deposits. The same we have seen is the case with the clays of 

 the 100-feet terrace. The true Carse-beds, however, differ in 

 many respects from these older estuarine accumulations. Thus 

 they as a rule contain no scattered stones and boulders, and are 

 not generally true clays, but rather silts. But although this is 

 their usual character, yet they are not so entirely stoneless as 

 some geologists have stated them to be. Here and there I have 

 detected small stones embedded in the fine silt and clay, some 

 of which measured as much as 6 inches across ; and occasion- 

 ally I have met with angular boulders a foot and more in 

 diameter. The largest block I have noticed was one which 

 measured 4 feet across. But stones and boulders of any kind 

 are certainly quite exceptional. Now and again the deposits 

 consist of tough, tenacious brick -clay, which does not differ 

 in appearance from similar brick -clays of glacial age. Their 



1 Mention is made in Sinclair's Statistical Account, vol. xvi. p. 555, of the 

 frequent recurrence in the Carse-clay of " sea-shells," but no special localities are 

 given. A polished stone implement is also said to have been found at Errol 

 along with shells. 



