622 



REV. THOMAS BROWN ON THE ARCTIC SHELL-CLAY 



little way above the foot-bridge, the base is found to consist of fine blue clay, pass- 

 ing upwards into a series of numerous sandy and clayey layers, arranged alter- 

 nately. One of these layers of clay, near the summit, deserves particular attention, 

 from the shells which it contains, and to which I shall afterwards refer (fig. 6.) 



4. The submerged forest of Largo Bay. Close to the Shooter's point, where 

 this section strikes the shore, it is found between high and low water mark, and 

 is seen passing out seawards. As it is an outlier, and not in contact with the 

 preceding beds, there may be some difficulty in fixing its position in the order of 

 succession ; but there seems good ground for placing it, as we have done, imme- 

 diately beneath the bed No. 3. The enclosed organisms show that it is the same 

 with the peat, No. 3 of Section II. ; and that it is evidently identical with bed 

 No. 2 of Section III. ; and we are thus able to show, approximately at least, its 

 true stratigraphical position. 



It will be observed that we learn from Section II., that it is older than the 

 so-called raised beach, and newer than the line of non-conformity— the break 

 formerly referred to — while Section III. shows that it is newer than the high- 

 level gravels and sands of the district. I was anxious to ascertain on what it 

 rested, as found on the shore, for the purpose of comparison. Mr Howie, of 

 Largo, who has paid much attention to this deposit, kindly met me on the spot. 

 The peat was dug through, and the underlying strata laid open, when we found 

 the following result. 



Four feet submerged 

 forest. 



Three feet laminated 

 sand, the layers about 

 half an inch thick. 



Gravel. 



Fig. 5. 



It will be observed how closely this corresponds with Section III. The 

 sandy and gravelly layers agree with the deposit which there underlies the peat 

 (2), and seem to indicate that this peat immediately succeeds the high-level gravels 

 of the district, coming in directly beneath the deposit No. 3 of Section IV. 



Having thus seen in detail the nature of these separate sections, it may be 

 well now to combine them in one view, and glance at the leading events in their 

 order. My object is to show at what point of our recent geological history the 

 Arctic shell-clay comes in ; and perhaps this will be most clearly seen if we 



