198 
DEPOSITS OF DOUBTFUL AOE. 
SuGcineoB, and not aquatic species. No sections of the Arctic 
Freshwater Bed are yet known except the four already 
described. 
The similarity of lithological character in all the deposits 
immediately beneath the Boulder Olay has necessitated the in¬ 
clusion of the Arctic Freshwater Bed in the Pre-glacial Series in 
the separate Sheet of cliff sections'^; but in the present Memoir 
it has been placed at the base of the Pleistocene Series, because 
the change from the climate of the Forest-bed, shown by the 
plants, is so great that it seems a misnomer to speak of the bed 
as Pre-glacial.” In this bed trees have entirely disappeared, 
and its plants include the dwarf Arctic birch and Arctic willow. 
Its fauna and flora show the first incoming of Arctic land 
speciest, and indicate a lowering of the temperature by about 
20 degrees,—a diflerence as great as that between the South of 
England and the North Cape at the present day, and sufficient 
to allow the seas to be blocked with ice during the winter, and 
to allow glaciers to form in the hilly districts. 
The whole of the strata lying between the Cromer Forest-bed 
and the oldest Boulder Clay on the Norfolk coast, seem referable 
to one or other of the two horizons just described as the Leda- 
myalis Bed and the Arctic Freshwater Bed. There are, how¬ 
ever, wide sheets of pebbly gravel about which nothing can be 
said, except that they lie between undoubted Pliocene strata and 
undoubted Glacial deposits. These gravels probably belong to 
several different horizons. Some of them appear to be shore 
deposits of the age of the Weybourn Crag, others may be coeval 
with the Forest-bed. Littoral equivalents of the Leda-myalis 
Bed may also be represented; and perhaps there may also be 
relics of still other horizons, of which the fossils are entirely un¬ 
known. Under these circumstances little can be done, except to 
give an outline of the distribution and general character of the 
deposits, and to indicate the few localities where more definite 
evidence may be obtained. 
A glance at the Geological Survey Map of the neighbourhood 
of Cromer, (Sheet 68 E.), will show that Pliocene deposits are 
traceable between Bacton and the River Ant at Honing. The 
strata immediately under the Boulder Clay at Bacton are generally 
the quartzite-gravels, quartzose sands, and laminated loams of 
the Forest-bed, and it is probably to this division of the Newer 
Pliocene that all the sections between Bacton and Honing belong. 
Similar gravels occur at Worstead; but the further they are 
traced from the coast the more difficult does correlation become. 
No fossils have been found in this area, except at Honing, 
where the eight species of mollusca recorded by Mr. H. B. Wood¬ 
ward are insufficient to fix the age of the deposit. It may 
* Horizontal Section, Sheet 127 {Geological Survey'). 
f The Glutton and Musk Ox are the only arctic land species yet known from the 
Forest-bed {see ante, p. 182). 
