MICHIGAN ACADEMY OF SCIENCE. 
107 
ORIGIN OF CONTINENTAL FORMS III. 
BY HOWARD B. BAKER. 
1. THE THEORY. 
In previous papers I have outlined the theory that the present con- 
tinents are the fragmentary remains of the crust of the Mesozoic earth. 
I have modified and developed the theory of the loss of earth mass 
first put forward by the Reverend Osmund Fisher and later by Pro- 
fessor Pickering, and have recorded certain conclusions prominent 
among which are the following: 
1. The present geographical plan is the result, primarily, of the 
separation of mass from the earth. 
2. This separation marked the close of the Mesozoic division of geo- 
logical time as determined by the sedimentary series of southern France. 
3. The separation was caused by extraterrestrial gravitation. 
4. It was brief. 
The theory as thus built up rests upon a large mass of geological 
data. General physical considerations, the evidence in favor of the 
former existence of extensive lands now lost, the fractured margins on 
the Atlantic ocean and the fact that opposite fractures may be fitted 
one to another upon the globe, these and many other lines of evidence 
go together to support the conclusions arrived at. At the same time 
the theory has biological aspects which are scarcely second in im- 
portance. It receives much support from both botany and zoology, and 
in return it offers to supply a new and a comparatively simple basis 
for pretertiary zoogeography. 
2. SURVIVAL OF LIFE. 
One of the numerous objections which the theory has to meet is the 
biological one that in a world-catastrophv of the nature claimed so 
much heat must needs be liberated that no life could survive. 
In reply to this we may say that the geological evidence is so strongly 
to the effect that the continental sheets separated at the time mentioned 
and we are so sure that life did survive from the Mesozoic into the 
Tertiary that a purely a priori objection has less force than it would 
otherwise have. Moreover, we know that at the end of the Cretaceous 
period there was great and widespread extinction of species of both 
animals and plants. 
To account for the survival of life we may observe that precipitation, 
altitude and atmospheric circulation would all combine to prevent 
unduly high temperatures over the lands of the earth. The smaller the 
land area the greater would we expect to be the destruction of life, and 
there is considerable reason for believing that such was the case. 
Upon the first rifting in the old crust, under the tidal distortion of 
