﻿24 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Nov. 20, 



or the chalk itself, or beds of gravel and sand ; though in these last 

 two they are not so regular and distinct as in the more consolidated 

 beds. 



15. If I am right in my views of these being due to the mechani- 

 cal action of water, and in identifying the deposit which fills them, 

 in the case of the Gaytonthorpe freshwater beds, with the Warp, — a 

 surface-soil, filling similar cavities in all subsoils, and at all elevations, 

 up to the summit-level of Norfolk, which is about 600 feet*, — and 

 if the surface-soil be, as I contend, an aqueous deposit of some kind 

 or other, it follows that these aqueous operations took place subse- 

 quently to the denudation of the upper and lower erratics, after a 

 sufficient interval had elapsed to permit the accumulation of from 1 

 to 20 feet of freshwater deposits ; and it becomes an interesting sub- 

 ject for future investigation, to trace the nature of the aqueous opera- 

 tions by which the soil was produced. 



16. On the other hand, if these phenomena at higher levels re- 

 sulted from the last wash of the glacial sea, during the emergence of 

 the land, and are distinct from those at Gaytonthorpe, it is an inquiry 

 no less interesting and essential to the right interpretation of the 

 history of the closing operations of the erratic period, where it is just 

 passing into that of the modern alluvium, to determine the true nature 

 of the Gaytonthorpe cavities. 



17. The general absence of marine remains from the upper erratics 

 of Norfolk, and the general absence of regular beds of these remains 

 from both upper and lower erratics in every district which I have 

 examined, — and I have now examined many in England, Wales and 

 Ireland, — are remarkable facts, and although perhaps referable, in 

 part, to causes not peculiar to the glacial period, we must not forget 

 that an extreme paucity of shells constitutes one feature of Polar seas. 



In Sir E. Parry's 'Voyages' we read occasionally of shells and 

 sand accompanying stones on the "dirty ice;" and we have occa- 

 sional mention of shells and corals brought up by the dredge ; but 

 attempts to procure shell-fish in sufficient quantities to afford a meal 

 for the crews invariably failed. The most varied and extensive haul 

 is recorded by Captain Beechy in Behring's Straits ; but, on the other 

 hand, we have the following notice in Sir John Franklin's first Voyage : 

 " On the spot where we landed were some mussels and a single piece 

 of sea-weed. This was the only spot on the coast where we found 

 shells." 



18. The amount of denudation to which the erratic tertiaries have 

 been exposed varies in different parts of Norfolk. It is least in the 

 northern portions, where the lower erratics have been scarcely reached ; 

 greater in South Norfolk and in the north of Suffolk, where the boul- 

 der clay is very generally exposed, the upper erratics occurring only 

 as outlying masses, and where the lower erratics have been cut through, 

 in some parts, as along the valley of the Waveney, down to the crag 

 and the chalk. The denudation is greatest of all on the west, where 



* I believe the recent triangulations of the Ordnance Survey have considerably 

 reduced this ; the former vertical angles having been taken with very inferior in- 

 struments. 



