90 PRESIDENT’S ADDRESS—SECTION C. 
by a third at least. Evidently expansion, in the form supposed 
by Mr. Reade, is not capable of producing a large mountain 
range. Indeed it is only by supposing the beds to arch up in a 
dome, as suggested by Professor Phillips, and independently by 
myself in 1872, that sufficient elevation can be attained. But this 
implies that mountain ranges are the remnants of plateaux, which 
I thought to be correct in 1872, but which has been amply disproved. 
There are also many other phenomena connected with the 
formation of mountain ranges which this theory fails to explain. 
In the first place, we have seen that no folding took place in the 
Alps and in the Himalaya, until the final upheaval began, which 
shows, either that the heat does not expand the rocks in the way 
supposed, or that the temperature does not rise until just before 
the final uplift takes place. To me the former seems to be by 
far the more probable, but Mr. Mellard Reade takes the latter 
view. He says: ‘It is extremely probable that while the area 
is subsiding, the isogeotherms are sinking also, and that the after 
raising of temperature, or rising of the isogeotherms is an 
extremely slow process.” In a later paper, “On Slickensides and 
Normal Faults,” published in the Pro. Liverpool Geol. Soc., 
1888-9, which he kindly sent to me, Mr. Reade says: ‘So slowly 
does internal heat escape by conduction through the present crust 
of the globe, that the blanketing of sediments, such as we assume, 
will not affect the temperature of the lower layers of the under 
crust till long after the compression induced by expansion in the 
upper layers of rock and in the sediments themselves, has com- 
menced the work of mountain upheaval.” I must confess that I 
do not understand either of these remarks, and both seem to me 
to be opposed to the laws of thermotics. Certainly they demand 
an explanation before they can be received as probable ; for, as 
we now know, geosynclinals take two or more geological periods 
to form, and it seems certain that the isogeotherms would rise 
nearly as rapidly as the sediments. 
The objection here noticed was urged by Mr. Hopkins in a 
Report to the British Association in 1847, and, in my opinion, it 
has never been fully met. He there says that Babbage’s theory 
is inadmissible, because, if it were correct, elevation and not 
depression ought to go with sedimentation ; and that deposition 
is so slow that whenever it ceases, the isogeotherms would very 
nearly have their proper position, so that expansion and deposi- 
tion would cease together. In 1873, I attempted to show that. 
sedimentation was, on the average, three times as rapid as the 
rise of the isogeotherms ; but, although this might occasionally 
be the case, I now think that it has been very unusual, and 
cannot have occurred in large geosynclinals, especially during the 
earlier geological periods. 
Another difficulty is, that gentle oscillations, without folding, 
have sometimes preceded the final uplift. If these elevations are 
