OF ELIE AND ERROL. 



633 



senting the Boreal province and the sub-arctic deposits. The one may shade into 

 the other, just as the provinces of the conchologist do ; but rightly viewed they 

 may serve as great landmarks, enabling us to classify and so to advance our 

 knowledge. With this explanation I would submit the following diagram, as 

 embodying a general view of the sequence of deposits through the whole of the 

 sections referred to in the preceding pages. It is not meant that the formation 

 of each underlying deposit was finished before the overlying bed began to be laid 

 down, at least in those cases where such deposits are found in separate localities. 

 Just as the Arctic shell-clay was (in the way explained above) partly cotempo- 

 raneous with the boulder-clay, so the blown sand, No. 1, may have been cotem- 

 poraneous in part with the raised beach, No. 2, and even with the river deposit, 

 No. 3. It is often impossible to establish the sequence in a rigorous way, so as 

 to exclude the idea of cotemporaneous formation in greater or lesser degree 

 among these superficial beds each in its own separate locality. But allowing for 

 this, the following will, I believe, be found to approximate closely the sequence of 

 the deposits : — 



Diagram showing the order of the Superficial Deposits. 



Sub-arctic BoreaL 



Fig. 8. 



Present Climate. 



1. Blown sand, with peat full of land shells. 



2. Raised beach. 



3. River sands and clays — Scrobicularia beds. 



4. Underlying peat — submerged forests — no shells yet found. 



5. High-level gravels. 



x Break in series of deposits repi*esenting the time of the Clyde beds, &c. 



6. Arctic shell-clay of Elie and Errol. 



7. Boulder- clay. 



VOL. XXIV. PART IIT. 



8 I 



