The Evolution of Clif nates. — Manson, 1 1 9 
whilst it existed at all it must have been the dominant factor, 
is of sufificient importance for us to look for some record of its 
subsequent practical extinction, and for marked distinctions 
between the mode and lines of heat distribution before and 
after its decadence. 
The gradually falling temperatures of the pre-glacial series 
of climate justifies the view that these temperatures were the 
direct "manifestations of a dying energy." It is highly prob- 
able that there were variations in this energy and that succes- 
sive increments were sometimes set free from the forming 
crust of sufBcient magnitude to sensibly raise the general 
temperature; and again that there were land masses of suffi- 
cient elevation above the general surface to make marked dif- 
ferences in local surface temperatures. There could have 
been no suspension of the laws which regulate the distribu- 
tion of heat as regards altitude. 
The great lessons which are distinctly recorded by fossil 
life are (i) that there was a non-zonal distribution of tempera- 
tures during and preceding the Ice age, and distinctly different 
from the zonal distribution now prevailing; (2) that successive 
ages of cooler and cooler climates followed one another cul- 
minating in a general Ice age. 
Between the widely separated periods just reviewed — the 
remote pre-Cambrian and the present- — there has existed a 
series of climates beginning with an age of ultra torrid tem- 
peratures and ending with an age during which elevated lands 
at all latitudes were loaded with ice hundreds and even thou- 
sands of feet thick. During each one of this series there was 
at sea level a uniform distribution of heat from pole to pole; 
during some of these climatic eras, and notably during the 
later ones, ice formed at all latitudes upon elevated regions; 
during the last of the series of climates, glacial conditions 
reached a maxinmm and marine life of arctie habit first 
appeared. 
Upon the close of this series there was inaugurated an age 
•of zonal distribution of temperatures distinctly controlled by 
solar energy and embracing in one era the extreme range of 
temperatures -torrid, tropical, temperate and frigid of the pre- 
glacial series of climates. 
During the earliest ages earth heat undoubtedly controlled 
