MICHIGAN ACADEMY OF SCIENCE. 
31 
and the plants and animals, in general, correspond, (albeit roughly) up 
to the end of Mesozoic time. 
So, as a conclusion from the foregoing investigation, Mr. Taylor's 
theory that the Tertiary mountain belt and crustal overthrusts explain 
the crustal movement indicated upon the globe may be said to be quan- 
titatively inadequate. Just how inadequate it is, we have seen in a gen- 
eral way; known foldings and thrusts and probable foldings and thrusts 
( such as those that may be thought to be submerged in the sea and those 
that are yet undiscovered on the land) such foldings and thrusts are 
capable of accounting for only a small fraction of the separation that 
is indicated by coastal parallelisms. But it is no less important to note 
that the theory is adequate for that small fraction. 
I conclude (1) that taken broadly Mr. Taylor’s theory is a most 
valuable contribution to the study of the origin of continental forms. 
(2) That it is true that slow crustal creep occurred in Tertiary time 
and resulted in mountain building substantially as described. 
(3) That Mr. Taylor’s theory is qualitatively insufficient to accom- 
modate lateral crustal movement as shown by certain coastal parallel- 
isms and by the Pacific convergences. 
(J) That it is quantitatively insufficient to account for more than 
a small fraction of the lateral crustal movement which can be shown to 
have occurred. 
(5) That Mr. Taylor’s theory, far from being an argument against 
or a substitute for the theory of separation of mass from the earth 
at the end of Mesozoic time, forms a most acceptable extension of it. 
What he really shows is how. throughout Tertiary time, the earth’s 
superficial structures went on slowly completing an adjustment, ap- 
proaching a new equilibrium after the destruction of the old; how the 
earth literally healed itself, filling in and closing up to a wonderful de- 
gree the huge Pacific depression. 
See how his story corroborates the other! and see how loss of mass, 
in turn, supplies him with one adequate first cause which his facts 
demand ! 
The various crustal sheets moved, crept, toward the Australian 
focus, and, if this was due to the existence of a depression there, then 
clearly, terrestrial gravitation was at the bottom of the matter. Never- 
theless there must have been other forces at work too, agitating or re- 
leasing forces which became intermittently active through Tertiary time. 
For mountain building seems not to have been a uniformly continuous 
process; it was intermittent. It took force to break the continental 
sheets loose and set them free to move as he shows that they did move: 
new rifts with separation had to accompany and permit Mr. Taylor’s 
crustal creep; and these events were intermittent, with periods of com- 
parative quiet between. In explanation of this aspect of the problem, T 
can quote with full approval the closing words of his paper and say 
that “one is inclined to reject all internal causes and to look to some 
form of tidal force as the only possible agency.” 
Just as I have argued that the Tertiary age was ushered in by the 
removal of mass from the earth and that this separation of mass was 
caused by extraterrestrial gravitation, to be. for the present, no more- 
explicit, so in the end. Mr. Taylor's crustal creep works out to the 
