500 8eeley — Gravel and Drift of the Fenlands. 



posited by percolating water ; and wliere the sand is coarse, there 

 the colour is dark. Hence I "wonld suggest that the gTavel may 

 have been coloured, since it was deposited, by waters draining 

 into it. 



The comminution and angularity of the flints of course indicates 

 the action of force, but whether of water ordy, or water and frost, 

 there is nothing to show. 



The physical geography demonstrates that the action of water 

 could only have been maiiae. And it could only have been by a 

 grand extension of the Wash over the Fenland, that the Upper Chalk, 

 and local rocks, and the old Boulder-clay were denuded to form the 

 gravels. A common section of false bedding from Barnwell repre- 

 sents such conditions of currents as are indicated by the shoals 

 of estuaries. 



/3, In the Cambridge area land and freshwater shells are found in 

 the gravel of most places. At Overton and Whittlesea the shells 

 have a land and brackish water character. At Hunstanton they are 

 marine, and such as now live on our coasts. At March they are not 

 only marine, but have an arctic aspect. At Doddington and Drayton 

 they are also marine. Those of Barnwell occur in the marl-band, 

 which Mr. C. M. Doughty finds to consist largely of Chalk and Upper 

 Greensand foraminifera. This, like the physical geography, sug- 

 gests a southern and S.E. origin for the Cambridge joortion of the 

 gravel. The shells are generally well preserved, but there is no 

 evidence that they lived near where now found. There are some- 

 times other thin marl beds above the main one. Now this may 

 either indicate that by upheaval the country became fluviatile and 

 lacustrine, or that from some imknown cause — such as silting up, 

 the sea lost its tidal action, and the estuaries only brought down fine 

 mud. Perhaps in some cases the former of these suppositions best 

 explains the sum of the facts ; but the other view may also be 

 true. Therefore, though the deposit is in the main marine, the 

 fresh water band shows that the change was gi'adual, aud that 

 since the period of coarse Gravel the country had become capable 

 of supporting many kiuds of life. 



The marine shells of Hunstanton by their aspect belong to the 

 close of the Gravel age. Those of March are in gravel, which is 

 contained between Boulder-clays, and obscure in age. Judging 

 from their arctic aspect they might belong to the Boulder-clay age, 

 but the Wash would be a very likely place to cut off and retain a 

 retreating colony. Eeconstructed Boulder-clay and gravel may both 

 be results of the same cause, and as those of Doddington are in no 

 way connected with Boulder-clay, their relation to that bed is 

 probably accidental. There is no reason for giving a different age 

 to the sea shells from Draji;on ; and hqre, though Boulder-clay is 

 near, gravel is the superficial bed. The asjDect of the country, the 

 shells of March, and considerations from the freshwater beds of 

 Cambridge gravels, induce me to regard this as the oldest of the Fen 

 gravels, probably formed between the coarse gravel and the marl 

 beds of the Gravel of the Plains. 



