TJic Laws of Climatic Evolution. — Ma/ison. 53 
potheses are not necessary. The areas over which the ice 
invasions once extended may and probably will be Vk'rangled 
over for generations to come, but no geologist nor physic- 
ist, who will take the trouble to observe a single glacier and 
to read what others have recorded, can dispute nor deny the 
fact that glacial extension has within a comparatively recent 
period been vastly more extensive at all latitudes than it is at 
present, and that successive retreat has been a marked 
characteristic of glacial conditions during the present era of 
geological time. The fact that glacial conditions are giving 
place to milder temperatures is recorded in all latitudes, and 
wherever glacial ice yet rests this record, although a slightly 
fluctuating one, is being legibly inscribed. The bare citation 
of the facts establishes the interpretation that solar energy is 
rewarming our planet after the chill of the Ice age — that the 
mean temperatures of the climatic zones now belting the earth 
have risen since that age, and that this rise is yet in progress. 
The Widespread Toiiperatc condition of the Tertiary. 
Throughout the whole of the northern hemisphere which has 
been reached by geologists, fossil fauna and flora have been 
found which establish the fact that during the Tertiary warm 
temperate conditions prevailed. During the middle Tertiary, 
palms flourished well within the Arctic zone.* Buried in bogs 
and mingled with gravel and boulders the bones of gigantic 
mammals are found in tropical Brazil. t These gigantic mam- 
mals and other types of life correspond with those found in 
Alaska, or in Patagonia; Tertiary life in Siberia records the 
same temperatures as that on the shores of the Mediterranean, 
so that from nearly one polar circle to the other, we are called 
upon to note, not only a once greater glacial extension, but 
also a preceding temperate age. The evidence of the existence 
of the one is no less conclusive than that of the existence of 
*Heer. Miocene Flora of North Greenland. Brit. Ass'n. Rept., 
■1886. 
Brit. Ass'n. Rept. 1870, p. 88. 
fBranner. The Journal of Geology, Vol. i. No. 8, p. 767. The pe- 
culiar distribution of boulders and gravel is ascribed by Dr. Branner 
to wave action, and to a reversion of the order of uplieavals and de- 
l^ressions appealed to by others to account for the Ice age. The dis- 
tribution of drift, as described by Dr. B., is that which Sir H. H. 
Howarth considers necessary to prove the glaciation of the Amazon. 
Valley. The Glacial Nightmare and The Flood, Vol. II, p. 495. Lon- 
don, 1893. 
