TRANSACTIONS OF SECTION C. 533 
to a great extent of the charm of his presence. It benefited, however, in the fact 
that the Presidential Chair was occupied by one of his most distinguished pupils, 
Jukes was one of those men the extent of whose knowledge is not readily 
fathomed. It has been my experience, and probably that of many others in this 
room, to find that some conclusion, formed after prolonged labour and perhaps 
fondly imagined to be new, has been arrived at years before by one of the old 
geologists. Such will be the experience of the man who follows Jukes’ footsteps. 
Turning to his Address given to this Section in 1862, we find much of what is 
now written about earth-movement and earth-sculpture forestalled by him, with 
this difference, however, that whereas the custom is growing of using a phraseo- 
logy which may sometimes be useful, but is generally far from euphonious, and 
not always intelligible, he states his arguments in plain, forcible English. 
It may raise a smile to find that Jukes thought it necessary in 1862 to combat 
the view that deep and narrow valleys had originated as fissures in the crust of 
the earth, and that the Straits of Dover must have been formed in this way, 
because the strata correspond on its two sides. But we shall do well to remember 
that the smile will be at the public opinion of that day, and not at Jukes himself, 
In no branch of Geology have our views changed more than in the recognition of 
the potency of the agents of denudation. In 1862 it was necessary to present 
preliminary arguments and to draw inferences which in 1904 may be taken as 
ranted, 
: The evidences of the prodigious movements to which strata have been sub- 
jected, and of the extent to which denudation has ensued, cannot fail to strike the 
most superficial observer. Both mountain and plain present in varying degree 
proof that sheets of sedimentary material originally horizontal are now folded and 
fractured. But after a momentary interest aroused by some example more striking 
than usual, glimpsed, it may be, from a train-window, the subject is probably 
dismissed with an impression that such phenomena are due to cataclysms of a past 
geological age, and have little concern for the present inhabitants of the globe. 
These stupendous disturbances, it might be argued, can only have taken place under 
conditions different from those which prevail now. We are familiar with moun- 
tain-ranges in which their effects are conspicuous ; we have carried railways over 
or through them and have been troubled by no cataclysmic movements of the strata. 
Apparently the rocks have been fixed in their plicated condition, and are liable to 
no further disturbance. Parts of the world, it is true, are subject to earthquakes 
accompanied by fissuring and slight displacement of the crust, but not even in 
earthquake regions can we point to an example of such thrusting and folding of 
the strata being actually in progress as have taken place in the past. Nor, again, 
can volcanic activity be appealed to, for some of the most highly disturbed regions 
are devoid of igneous rocks, Volcanic eruptions are more probably the effect than 
the cause of the disturbances of the crust. Nowhere in the world therefore, it will 
be said, can we see strata undergoing such violent treatment as they have 
experienced in the past. How, then, can we dispute the inference that the forces 
by which the folding was produced have ceased to operate ? 
Before accepting a conclusion which would amount to admitting that the 
globe is moribund and that the forces by which land has been differentiated from 
sea have ceased to act, we shall do well to look more closely into the history of the 
earth-movements to which any particular region has been subjected. The investi- 
gation is one which calls for the most intimate knowledge of the geological 
structure, and, as time will admit of my dealing with a small area only, I shall 
confine my observations to England and Wales, selecting such facts as have been 
established beyond dispute. ; . 
At the outset of the investigation we find reason to conclude that the move- 
ments, so far as any one region is concerned, have been intermittent. Evidence 
of this fact is furnished wherever any considerable part of the geological column 
is laid open to view. Sheets of sediment, aggregating perhaps thousands of feet in 
thickness, have been laid down in conformable sequence, all bearing evidence of 
having been deposited in shallow seas, The inference is inevitable that that 
period of sedimentation was a period of uninterrupted subsidence. But aooner or 
