90 REPORT—1858. 
outline of these granitic areas, and suppose for a moment that these boundaries are 
great faults lifting up the strata some 5000 or 10,000 feet. 
Again, if these granites and syenites were all eruptive from some unknown depth 
common to all of them, it would be difficult to account for the distinct and separate 
type or character which each possesses. 
I venture to come to the general conclusion, therefore, that both positive and 
negative evidence favours the hypothesis, that the whole phenomena of the granitic 
and igneous rocks of the Lake District are a grand and very interesting exhibition 
of metamorphic action on a large scale. I feel that there is still a difficulty remain- 
ing which will occur to most of us. We have been accustomed to look to the violent 
eruption of those igneous masses as the cause of the upheaval, fractures, faults, and 
contortions of these mountain regions. Take away this cause, and what adequate 
causes have we left to which such effects can be attributed ? 
This inquiry would lead me to enter upon a subject of very high interest, but so 
wide and large in its bearings, that I feel it almost presumptuous in me to deal with 
it at allin such a presence as that I see round me. I may venture to give a mere 
outline of what has occurred to my own mind, which may serve as a starting-point 
to those much more competent than I am to treat of such a subject, and may at least 
afford some suggestions that may be worked out. 
Since the time when Hutton and Playfair, Cuvier and Smith re-formed and re- 
founded, as it were, the theory of geology, the exertions of geologists have been 
chiefly directed to the completion of the vast labour of making out the stratigraphic 
order of position, and the accompanying series of organic remains of the whole stra- 
tified crust of the earth. It is only from time to time, and more especially of late 
years, and by no one more than by our present President, that the study of the 
Dynamics of Geology has occupied much attention. 
It would seem that the progress of geology must shortly bring these questions 
much more prominently forward. The point to which I wish at present to draw 
attention, is the expansion and working out of some very remarkable and important 
suggestions first made by Babbage in 1834, and illustrated by Sir John Herschel in 
a letter to Sir C. Lyell, in 1836, on the causes which may have produced the eleva- 
tion or submergence of continents. I must refer to the letter itself for a complete 
exposition of Sir J. Herschel’s view; I can only now quote such portions as are 
immediately necessary to my argument. 
The results arrived at appear to be :— 
1. The transference of solid matter by abrasion from continents, and its deposit 
at the bottoms of oceans, disturb the equilibrium both of heat and pressure. The 
isothermal lines of internal heat will rise under the bottom of the ocean and fall 
under the continent ; the strata under the ocean will be heated and thereby expanded, 
and thus the bottom will be raised. Again, the whole crust of the earth being sup- 
posed to be floating upon a fluid ocean of melted rock, the increase of weight in 
some parts and diminution in others will tend to crack or break the crust in its 
weakest parts, 
2. These cracks or fractures, produced by general and constantly acting causes, 
will give rise to volcanic vents and earthquakes. Thus volcanic phenomena become 
of secondary importance; they are not the causes of the elevation of continents and 
mountain chains, but the consequence of such movements produced by far more 
general and constantly acting forces. 
I may remark, that in all these speculations on the effects which the expansion of 
strata caused by the incursion of heat from below will produce, the expansion in a 
vertical direction alone has been adverted to. 
But I think it is evident that the expansion which will take place in the bottom of 
an ocean 1000 or 2000 miles wide, will be very much greater in a horizontal or late- 
ral direction than vertically, in the proportion which a length of 1000 miles bears to 
the thickness of 20 or 30 miles. 
The enormous lateral thrusts which will be thus produced, seem to me to consti- 
tute an adequate dynamic force for producing those vast wave-like wrinkles and con- 
volutions and tilting up and even inversion of strata which we see in mountain 
chains: for on the supposition that the bottom of the sea, subject to tension by ex- 
pansion from heat, would give way at the weakest points, we are enabled to explain 
