1886. | some of its Apparent Causes. 33 
ants of the Pliocene-Tertiary life of the same regions. Again, 
peculiarities inthe distribution of plants and animals in North 
America and Northern Eurasia indicate strongly that there was 
an extensive migration southward down the Atlantic and Pacific 
borders of the continents as the glacial cold crept over the once 
populous circumpolar regions. 
A second series of causes of extinction arose from the eleva- 
tion or depression of extensive regions of the earth. The par- 
oxysmal, elevatory process in the formation of the Cordillera of 
North, and particularly South America, involved corresponding 
more or less rapid changes in the flora and fauna of the Pacific 
Coast regions of those continents. In South America, particu- 
larly, during the Quaternary period, though there was no glacial 
period north of Patagonia, the extinction of life was widespread 
and marked. 
As observed by Darwin and Alexander Agassiz, within historic 
periods there have been paroxysmal upheavals over thousands of 
square miles, if not over the whole extent of the Western Andean 
plateau. 
For example, in 1822, after an earthquake, the coast line of 
Patagonia and Chili was suddenly elevated from two to seven feet 
above the level of the ocean. In 1835 Darwin, while at Valdivia — 
on the coast of Chili, experienced the earthquake which devasta- 
ted Conception, and he says his “compassion for the inhabitants 
was almost instantly banished, by the surprise in seeing a state of 
things produced in a moment of time, which one was accustomed 
to attribute to a succession of ages. In a single day, Feb. 2oth, 
this earthquake shook the coast of South America over an area 
600,000 square miles, and the whole coast line of Chili and Pat- — 
agonia was elevated from two to ten feet above the sea level.” 
Darwin in his Voyage of a Naturalist remarks: “ At the island 
of S. Maria (about thirty miles distant), the elevation was greater ; 
on one part, Captain Fitz Roy found beds of putrid mussel-shells ` 
still adhering to the rocks, ten feet above high-water mark; the 
inhabitants had formerly dived at low-water spring-tides for these 
shells. The*elevation of this province is particularly interesting 
from its having been the theatre of several other violent earth- 
quakes, and from the vast numbers of sea-shells scattered over the 
land, up to a height of certainly 600 and, I believe, of 1000 feet. 
At Valparaiso, as I have remarked, similar shells are found at the 
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