Fisher — Denudations of Norfolk. 555 



where the strata consist of coarse gravelly Drift, as for instance in the lower beds 

 of the Middle Drift, which form the picturesque hills about Cromer. If the 

 surface of the lower ground be examined, where the rich land occurs upon the 

 upper portion of the Lower Drift, as it is seen in section in the cliffs, we find no 

 great accumulation of any such material, as it seems to me must have been left be- 

 hind, had the denudation of the superincumbent Middle Drift been due to its 

 having been gradually washed away by rain or melting snow. This is a negative 

 argument. 



On the other hand, I have long had my attention directed to the condition 

 of the surface in districts consisting of sand, gravel, and clay, and I think that I 

 see unmistakable evidence of the soil having been moved in a plastic state to the 

 depth usually of from three to five feet ; furrows being often formed which run to 

 a greater depth. These must not be confounded with sand pipes in calcareous 

 strata, which are chiefly due to solution, but they occur over all kinds of strata 

 ahke. Often we see, in the manner in which the movement of the surface has 

 taken place, evidences of pressure. The material which has been thus pushed 

 onwards consists of a mixture of the subsoil with material derived from the higher 

 grounds. Stones are suspended in clay, and not always collected at the bottom, 

 as if the matter had been arranged by water (though sometimes that is the case). 

 This is the material which I have called " trail. "^ It is not identical with the 

 "warp," which is a somewhat similar, but more recent and superficial covering 

 derived from the action of the weather upon the trail. The warp contains organic 

 remains, but I believe the trail never does so. 



I have suggested that this peculiar condition of the surface, as also certain other 

 phenomena, such as the reversal of the edges of slaty lamince,^ as described by 

 Mr. Mackintosh, may be due to land ice ;' and I have shown that, on Mr. Croll's 

 theory of climatal changes, it is probable that a condition of things, conducive to a 

 glacial climate, probably existed in this country about iio.ooo years ago.* But I 

 am open to conviction from any one who will explain the phenomena on a different 

 supposition. 



The remote age which I have assigned to the trail on the Glacial theory may ap- 

 pear startling, at least to those more careful geologists who keep note of their drafts 

 upon the bank of time. But I have shown that the trail is so old, that considerable 

 geological changes have taken place since its formation. It is older than the Scrobi- 

 cularia mud, which skirts our estuaries, and older than the submerged forests which 

 lie beneath them,^ in which Elephas primigenius occurs. 



But putting aside the argument for absolute dates from climatal considerations, 

 and reverting to the usual geological scale of relative antiquity, we have evidence 

 from the manner in which the lower parts of valleys are occupied by forest grounds, 

 covered with ancient mud containing estuarine shells, and those covered again by 

 turbaries,^ that the present configuration of the surface, with the exception of very 

 minor subsequent modifications, dates back to a far distant and prehistoric age. For 

 it is evident that the same configuration of hill and dale existed, and indeed must have 

 been formed, when the land was higher than it is now, and when those portions of 

 the valleys, which are now either drowned, or covered by marsh land, were consi- 

 derably raised above the sea. 



But carrying back our observations to a period long antecedent to the submarine 

 forests, we find evidences of a similar cycle of events. We have a form of surface 

 almost, but less nearly, identical with the present one, and an older drowning of 

 the lower valleys. The former surface exhibited in the section of the old valley at 

 Mundesley belongs to this period, and the marine deposits of the Valley of the Nar 

 probably to its later phase. As far as I am at present aware, the period of eleva- 

 tion to which I am referring is characterised by the common occurrence oiElephas 

 antiqinis in company with /r//;z/^^«zz/j-, 2S\.^ z\.%o oi Rhinoceros leptorhinus. Unto 



1 Journ. Geol. Soc, vol. xxii. p. 553. In a small pit adjoining Mr, Barnes' brick pit jit 

 Surlingham, I saw a fine exhibition of the trail with stones from the Boulder-clay, one of which 

 was about twenty-five pounds weight. 



2 Journ. Geol. Soc, vol. xxxiii., p. 323. 



3 Geol. Mag., vol. III., p. 483. ♦ Ibid., vol. IV., p. 193. 

 * Journ. Geol. Soc, vol. xxii., p. 553. 



6 The shells from Downham, near Ely, are Scrobicularia Cardium, &c., and there was a forest 

 ber.eith, and the bones of beavers are found associated with it. 



