100 
THE MEDITERRANEAN NATURALIST 
told him that the deepest and oldest rocks were 
the most crushed and folded, whereas on the “level- 
of-no-strain” theory they ought to be the least 
disturbed. 
These sentiments— for a good deal of it was 
geological sentiment and righteous indignation 
against mathematicians — caused me much amuse- 
ment. Anyone may see for himself who takes the 
trouble to study my “Origin of Mountain Ranges” 
that similar geological arguments are therein used 
to show that mountain ranges have not been 
thrown up by compression induced by the earth’s 
contraction, which compression, as is proved by the 
discovery of the level-of-of-strain in a cooling 
globe, does not even now affect the earth’s crust 
below the depth of a few miles. This was, in fact 
one of the many reasons which induced me to look 
for another origin for the earth-foldings distin- 
guishing mountain regions. 
The speakers referred to at the British Associa- 
tion, unconsciously begging the question, took it 
for granted that earth-foldings and contortions 
could be produced in no other way than on the 
shrinking-apple system, therefore the “level-of-no- 
strain” was a myth — an invention of the. enemy, 
the mathematician and physicist. Q.E.D, Let us 
now see if there is not a method of explaining these 
wonderful evidences of pressure found in mountain 
regions without invoking secular contraction as 
the direct cause, and in a way more consistent 
with geological facts, which, as I before said, must 
be our guide and court o appeal in forming theo- 
ries of the earth. 
As already pointed out, the effect of the deposi- 
tion of sediment is to raise the temperature of the 
underlying rocks. For the sake of employing 
round figures in illustration, let us say the heat 
gradient or rise of temperature downwards in a 
given area of sedimentation is 100° per mi.le = l° 
per o2'8 feet, then the accumulation of 10 miles in 
thickness of sediment would raise the temperature 
of the underlying rocks IOC-'.", the sediment them- 
selves taking at the surface the mean yearly tem- 
perature of the locality say 50° and at the base 
being 1000' hotter. The mean rise of temperature 
of the 10 miles of sediment would then be '500°. 
SuHi a thickness of sediments may seem astoun- 
ding to 1 hr vsc ho u e unfamiliar with geological 
facts, but the most eminent geologists tell us that 
the combined thickness of the strata of many great 
mountain ranges reaches this limit. As such a 
depth is twice as great as any known part of the 
ocean, it may justly be inferred that the weight of 
the pile of detrital matter has helped to displace 
the foundation matter of the globe upon which it 
has been built. 
The underlayers at some unknown depth in the 
earth have flowed laterally from the area of sedi- 
mentation outwards, but of the manner in which 
the surrounding rocks are affected we have as yet 
no direct geological evidence. 
It must be understood that these operations of 
Nature take periods measured by millions of years 
and during this time with increasing weight, heat, 
and chemical action, the unsoliditied deposits get 
consolidated into beds of rock capable of with- 
standing considerable lateral stress. As they are 
solidifying they are increasing in temperature and 
exerting a lateral thrust which is buttressed by 
the surrounding rigid area of old rocks, while the 
beds themselves are kept from rising in folds by 
the weight of sediment with which they are 
loaded. 
But not only are the sediments themselves affec- 
ted by these internal stresses: the underlying old 
and rigid foundation rocks are subjected to still 
greater stresses, as their mean temperature has 
risen twice as much as that of the overlying sedi- 
ments. In addition, they are less capable of being 
squeezed into a smaller compass. 
We see, therefore, that all the rocks in the area 
of sedimentation are subject to two opposite for- 
ces — one of increasing expansion by heat, and the 
other of increasing and countervailing vertical 
pressure by loading. The piling up of the sedi- 
ment at first proceeds at a more rapid rate than 
the mean rise of temperature of all the underlying 
crust of the earth due to the deposition of the 
imperfectly conducting covering of new rocks. The 
sediments themselves also become worse conduc- 
tors of the outflowing heat of the globe, as they 
lose their water by pressure, wet rock being a much 
better conductor than dry rock, as conclusively pro- 
ved by experiments in the laboratory. 
To what extent, then, can mechanical pressure 
resist the tendency of rocks to increase in bulk by 
rise of temperature. We really have no satisfactory 
data to go upon as regards cubical expansion, but 
