192 PROCEEDINGS OP THE GEOLOGICAL SOCIETT. [Jan. 1 1 



We see, then, that after the estuarine mud was raised above the reach 

 of the tide, oak-trees grew upon it, and, since these have been cut 

 down, a thick bed of peat has gradually accumulated over their 

 roots. All this, of necessity, implies the lapse of much time. The 

 extensive masses of blown sand that have accumulated on some parts 

 of the coast since the land attained its present level afford addi- 

 tional evidence of the length of time that has elapsed since the 

 event. The most remarkable of these in the district of which I 

 am treating are the sands of Culbin in the Moray Pirth, of Eorvie 

 and Foveran on the Aberdeenshire coast, and of Barry at the 

 entrance to the Firth of Tay. These great heaps seem to have 

 some connexion with the rivers entering the sea in their neigh- 

 bourhood. Thus the masses at Culbin are probably derived in a 

 great measure from the sand brought down by the Spey, the Find- 

 horn, and the Nairn. Those on the coast of Aberdeenshire from 

 what has been brought down by the Dee, Don, and Ythan, while 

 the accumulations at Barry probably represent to some degree the 

 sand of the Tay and the Earn. 



h. Shell-mounds and Chipped Flints. — Another thing worthy of 

 notice is the occurrence of old shell-mounds on the raised beach. 

 Several of these occur at the mouth of the Ythan, in the desolate 

 tract of drifted sand just mentioned, more especially on the north 

 side of the river. There are hills of blown sand here 120 feet high. 

 The shell-heaps are generally of an elliptical form, and from 30 

 to 90 yards in length. I have examined several of them, in com- 

 pany with my friend Mr. Eobert Dawson of Cruden.. We found 

 them to consist usually of a thin stratum of decayed shells, repo- 

 sing on a surface of drifted sand ; but in one of them the mass of 

 shells is 4 or 5 feet deep. These sheUs belong to the edible 

 species of Mollusca now inhabiting the adjoining estuary, being 

 chiefly mussels, cockles, and periwinkles. Mixed with them we 

 frequently find some black carbonaceous matter like charred turf, 

 together with pieces of burnt twigs. There are also a great num- 

 ber of stones, many of which appear to have been in a fire, and 

 occasionally the sand underneath the spots where the charred turf 

 and burnt stones occur is somewhat redder than usual, as if it had 

 formed a hearth. Pieces of artificially chipped flint occiu? on the 

 surface of some of the mounds, and are found abundantly in the 

 immediate neighbourhood of one of them. A few of these flints 

 lying on the mounds seem likewise to have been exposed to heat. 

 Some teeth and spHt bones are also to be met with, but we found 

 no pottery, nor anything made of metal in the Forvie mounds. 

 The quantity of stones and pebbles on the surface of some of 

 them is a cmious feature. They seem to have a considerable re- 

 semblance, in many respects, to the Kjokkenmoddings of Denmark. 

 Their antiquity, however, does not seem to be very great. The 

 base of the largest of them is not 4 feet above the present reach 

 of the tides in the estuary of the river, which shows that the land 

 must have been as high as it is at present when they were formed. 

 They are therefore later than the raised beaches and estuarine beds; 



