420 Reviews—C. Fox-Strangways—Jurassic Rocks of Britain. 
until the boring-rod has perforated the central mass of Kimeridge 
Clay in the Vale, the problem cannot be regarded as completely 
solved. 
The general connection which exists between ‘Scenery and 
Denudation” has exercised the mind of many a field geologist; yet, 
as Mr. Strangways truly observes, there are few districts in England 
where the simplest forms of denudation are more clearly exposed 
than in the Tabular Hills and along the sea-coast; and he takes 
care to point out that the inequalities of the surface are mainly due 
to erosion, or to what some of the provincials would term “a wash 
out.” He lays much stress upon initial direction in the formation 
of valleys and gorges, as being due to the original slope resulting 
from stratigraphical conditions. Since a large portion of the Jurassic 
rocks slope inwards towards the Vale of Pickering, a sort of horse- 
shoe arrangement is the result, and many interesting cases are cited. 
No one at this time of day is likely to call in question the general 
proposition that the valleys and gorges which are found in this 
district result mainly from meteoric denudation; but the period 
during which such sculpturing has been effected is not always 
equally clear, and there are two well-known and extremely interest- 
ing cases, where the conclusions of Mr. Strangways appear not 
a little startling. One of these cases relates to the Derwent as it 
enters the Vale of Pickering, the other to the Derwent as it leaves 
the Vale, where it becomes the sole conduit of the accumulated 
waters of so many springs and brooks. 
To appreciate these points fully one ought to know the district. 
But it may suffice to say that the Upper Derwent, in its course from 
the higher moorlands, after flowing past Hackness, enters a tolerably 
wide valley, which has a general easterly direction and leads to 
the sea-coast in about five miles. This Scalby valley has all the 
appearance of being the true continuation of the Valley of the 
Derwent, and Mr. Strangways points out that the natural tendency 
of the original stream would be towards the east at this spot, owing 
to a local anticlinal axis. In fact he has no doubt that this was the 
old course of the Upper Derwent. Yet to the surprise of everybody 
who has visited the spot, the Derwent, instead of following a good 
wide valley almost straight to the sea, has taken the trouble to cut 
a narrow gorge some 300 feet deep and one-and-a-half miles in 
length through the Middle Oolites, direct for the Vale of Pickering, 
and almost at right angles to what seems to have been its previous 
course. He considers that this result has been attained through 
the damming up of the lower end of the Scalby valley by glacial 
deposits, or possibly by the North Sea ice itself. If the wholé of 
this amount of work was done since the commencement of the 
principal glaciation, we are fain to suppose that no inconsiderable 
portion of the sculpture of the country has been effected in Pleisto- 
cene times. 
The case of the long and sinuous breach in the Howardians by 
which the Lower Derwent escapes into the Vale of York is some- 
what analogous, as he considers that this has been effected by the 
