560 Norwich Geological Society. 



ISToKwiCH Geological Society. — Monthly meeting, September 3rd 

 (continued). The Eev. J. Gunn, M.A., F.G.S., President, in the chair. 

 The President read a letter from Mr. Searles V. Wood, jun., having 

 reference to the so-called deposits of the old estuary of the Yare, 

 Mr. Wood said, " I have been induced to doubt whether the beds 

 described by Mr. Prestwich, as covering the London-clay in Sir E. 

 Lacon's boring at Yarmouth, be what he calls them, viz., the deposits 

 of the old estuary of the Yare. There may be nothing in my 

 doubts, but I will explain them. The depth to which these deposits 

 descend is 171 feet, the upper fifty feet being, according to M!r. 

 Prestwich, blown sand. Now as the town of Yarmouth stands only 

 from ten to fifteen feet above the present level of the Yare, this depth 

 of 171 feet would, on Mr. Prestwich's view, imply that the estuary of 

 that river was originally 28-| fathoms below the town of Yarmouth, 

 and was completly silted up to the marsh level. Such a depth, how- 

 ever, I find to be three times the deepest point inside the sands 

 forming the Yarmouth Eoads, and more than twice the average depth 

 of the North Sea, which only exceeds seventeen or eighteen fathoms 

 in a few deep places far out towards Holland. Moreover, it is double 

 the greatest and three times the average depth of the estuary of the 

 Thames, where it is fifty miles across from Harwich to the North Foreland. 

 It exceeds the depth of the English Channel, between Sussex and 

 France, and only one narrow submarine channel in the Straits of 

 Dover equals it. Moreover, if the thickness of the Crag and Chilles- 

 ford beds on the east side of Norwich be added to the base of Corton 

 cliffs, it would only take off from this 171 feet, at the most, 

 21, leaving 150 feet to be added to the thickness of the London- 

 clay, which the boring showed to be 310 feet under the 171. This 

 would make the thickness 460 feet for the London-clay, or more 

 than its maximum known thickness in its thickest part, viz.. South- 

 east Essex. Under these circumstances I cannot help having a 

 suspicion that the so-called estuary beds are the prolongation of the 

 Cromer beds, which, in the form we see them at Hasbro', seems to 

 resemble the beds pierced in the 171 feet boring, or rather in the 

 lower part of that boring, say the lower 120 feet. If there be any- 

 thing in this, the only way to determine it would be to put down a 

 borer from the base of Corton cliff, and learn whether these beds 

 are present there below the red loam sand and Boulder-clay of that 

 cliff. Of course we can suppose the Yare estuary excavated to this 

 depth, with a proportional increase in the depth of the adjoining 

 North Sea ; but when we recollect the rapid way the coast wastes, it 

 is difficult to suppose that the cliffs forming this estuary on either 

 side of the Yare, now represented by the hills north and south of 

 the river (which are only six miles separated) , would not have been 

 wasted by the agency of deep waters of such an estuary during the 

 long period required for silting up 171 feet, so as to push them back 

 to a much greater width than they now possess. If the Yare has 

 thus been silted up, why have not the other rivers of the east coast?" 

 The President said Mr. Prestwich came to the conclusion he did by 

 examining the shells ; if he had seen the Tellina ohliqua, or any of 



