90 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [Jan. 9, 



of in this paper is more recent, not only than the Bonlder-clay No. 7, 

 by the period required for the destruction of the latter and the sub- 

 sequent formation of the great sheet of plateau -gravel No. 8, but 

 than the gravel itself, by the time necessary for the erosion of a deep 

 valley, at this point three quarters of a mile in width, and nearer 

 Yarmouth much wider. 



That it is not the Boulder-clay No. 7 thrown down by a fault, 

 and exposed by the erosion of the valley, is, I think, conclusively 

 proved by the fact that, in both the cases I have mentioned, the de- 

 posit rests directly on the chalk. 



At Bawburgh, on the contrary, five miles to the west of the Trowse 

 pit, and eight miles from that at Thorpe, there are several exposures 

 of Boulder-clay which occur in a precisely similar position in the 

 same valley, but whose relative position to the chalk is not shown 

 in the sections. I believe this clay is identical with that at Trowse 

 and Thorpe ; but as its junction with the chalk is not shown, it may 

 be that it is there the Boulder-clay No. 7 faulted to a lower level, 

 and underlain of course by the beds that intervene between it and 

 the chalk along the sides of the valley. At Trowse and Thorpe 

 there are no beds whatever between the chalk and the clay. 



A reference to fig. 3 will show that, while to the south of the 

 River Yare, at Bramerton, nearly two miles distant from the pit, and 

 obliquely across the valley, the Boulder-clay (No. 7) still remains, 

 there is not a vestige of it left on the side of the river where the 

 deposit in question occurs, the Boulder-clay having there been de- 

 stroyed not merely before the valley was eroded, but before the great 

 sheet of plateau-gravel of Household Heath was deposited. The 

 mass of the new deposit remaining at Thorpe is a quarter of a mile 

 in length and 10 feet thick ; consequently any hypothesis of its being 

 due to a slip of a portion of bed No. 7 into the valley seems inadmis- 

 sible without adopting the extreme supposition that it travelled 

 across the valley from the Bramerton table -land. 



In the case of the Trowse pit (fig. 2) an outlier of the Boulder- 

 clay (No. 7) still remains above the spot where it occurs ; but here 

 the finely laminated sands and clays overlying it, the stratification 

 of which indicates an upheaval and denudation, are as strong an 

 argument against its being referable to a slip as the non-occurrence 

 of the Boulder- clay above it is in the other instance. 



January 9, 1867. 



George Clark, Esq., of Dowlais ; James Eccles, Esq., Springwell 

 House, Blackburn ; William Harris, Esq., M.A., Osbourne Villas, 

 Windsor; and J. Charles Pooley, Esq., E.R.C.S., 1 Raglan Circus, 

 Weston-super-Mare, were elected Eellows. 



The following communication was read : — 



