Seeley — Gravel and Drift of the Fenlands. 497 



over the country, and originally did not merely cap hills or fill 

 valleys as it does now — at least, in this district. If this is assumed, 

 it is difficult to explain what has become of all the solid substances 

 which would be contained in a regular stratum of even 20 feet of 

 drift, or whence such a deposit could have come. And I should 

 rather be prepared to believe that the Boulder-clay was only par- 

 tially spread than that its solid rocks and fossils could melt into 

 thin air. In many cases what is now the higher land may have 

 arrested the passage of the drifting ice, and the melting would 

 thicken the Boulder-clay. 



I am far from asserting that all the Boulder-clay was formed 

 during this period of subsidence ; or, in this manner, some at least 

 was constructed during the subsequent age of uprising. 



There can be no doubt that the gravels of Hunstanton came from 

 the Yorkshire area. The presence of a sandy variety of the Hun- 

 stanton Eock, rounded into water-worn boulders, would seem to 

 indicate a similar origin for the coarse gravel of the Gog-magogs. 

 The brown Boulder-clay of Elsworth, where it rests on the stratified 

 beds, has a large per centage of Oxford and Kimmeridge clay fossils 

 with some of the Lias. Bluntisham abounds in Liassic fossils, with a 

 few from Upper Chalk. This too may indicate a northern origin. 

 Fossils from the clay at March are more local. At Bourn and 

 Longstow, with many local forms, there is a large proportion which 

 may have come from the northern oolites. So that the contents tend 

 to show that much of the material of Fenland Boulder-clay came from 

 the Yorkshire area. Against this is the fact that on all the hills in 

 the Fens and its borders the drift and coarse gravels are found only 

 on the south and south-east slopes, which, however, shows that by 

 subsequent denudation they were removed from the sides facing the 

 old sea. 



2. Coarse Gravel. 



The Fenlands offer few memorials of what happened during the 

 succeeding age of elevation. There is no contorted drift as in 

 Norfolk and Suffolk. 



In this area Boulder-clay is rarely overlaid by gravel. One 

 instance may be seen in the Ely Clay pit ; others on the Hog's 

 Back, going to St. Neots ; others on the Gog-magogs. All are cases 

 of gravel on hiUs. The gravel of Ely is partly a fine deposit, 

 and shows abundant evidence of having been regularly arranged 

 in water. It does not cover the Boulder-clay, but only fills a 

 cavity in it ; and from its small extent looks as though denuded : 

 it is largely made up of flints. 



In the gravels are found, only more sparingly, all the rocks 

 which compose the Boulder-clay. But there is something more, for 

 in this district, where the hills are of Chalk, the mass, especially of 

 the low land gravels, consists of flint. At Peterborough, where the 

 high land is oolite, the gravel consists, to some extent, of rounded 

 calcareous pebbles. At Hunstanton it is chiefly sand. 



I do not suppose that the existence of coarse gravels on hills, like 



VOL. 111. — NO. XSIX. 32 



