H. W. Monckton — Gravel-Flats of Surreij and Berks. 511 



On the side of the Fox Hills (Sheet 285) there is a sheet of gravel 

 south of Mitchet House, with a level of about 250 feet; and at 

 Eversley, Shinfield, and Hurst, in Sheet 268, there are flat expanses 

 of gravel almost flush with the alluvium of the rivers Blackwater 

 and Loddon, and at levels of 180 to 120 feet. 



There are many other sheets of gravel in this neighbourhood, but 

 I have mentioned sufficient to show that there are here a series 

 at very various levels, from the high ground of Cassar's Camp, 

 Aldershot, down to the level of the alluvium of the rivers which 

 drain the area. 



If we continue our course down the Thames we find similar 

 gravel-flats practically down to the present level of the sea. 



I have said that these gravels consist mainly of chalk-flints, but 

 they also contain other stones, and a careful examination of these 

 convinced me that the gravels are of fluviatile origin, the nature 

 of their composition depending upon the geological structure of the 

 drainage area of diff'erent rivers.' 



If, then, these sheets of gravel are, as I believe, river gravels, they 

 must all have been originally deposited at the bottom of a valley, 

 and where, as in several of the cases above mentioned, they are now 

 on plateaux or terraces, this position must be due to denudation, 

 which has destroyed the sides of the valleys since their deposition. 

 It is pretty clear that this is the case, for every stage may be found 

 between the gravel terrace in a valley and the gravel-capped plateau 

 with valleys all round it. 



There is a good example at Maidenhead, where there are three 

 well-marked terraces of gravel, as shown in a sketch-map by 

 Mr. Whitaker.^ They are l^ung on the side of the Thames Valley, 

 but if we follow the highest terrace southwards we find that 

 between Bray Wick and Maidenhead the progress of denudation 

 has been sufficient to make the terrace into a plateau with valleys 

 all round it. 



Now it has for some time seemed to me that these gravel-flats 

 may have something in common with the terraces which we see 

 in so many places on the coast and in the fjords of Norway. In the 

 first place there are several points of resemblance — 



1. They are formed of gravel and sand. 



2. They have a flat and somewhat sloping top. 



3. Several flats occur one above the other. 



4. Between the flats there is a steep slope. 



5. They appear to be mainly the work of rivers. 



Now the explanation of the Norwegian terraces which, I believe, 

 finds favour in Norway is as follows : — 



The rivers carry with them sand, clay, and small stones, much of 

 which is deposited in the valleys. The remainder sinks to the 

 bottom before the mouths of the rivers in the sea or fjords, and 

 is spread oat as a slightly inclined plain where circumstances are 



1 Quart. Joiu-n. Geol. Soc, 1892, vol. ilviii, p. 29 ; 1898, vol. liv, p. 184. 



2 «' Geology of London " : Mem. Geol. Surv., 1889, vol. i, p. 391. 



