3i6 The American Geologist. Kovember, looi. 
sions, crowned the ridg^e of Scarboro' Heig^hts, attaining- to- 
gether the thickness of 203 feet. 
Several species of the nioHuscan fauna which earhest came 
into the region of Toronto, following- the retreat of the ice, 
were later unable to survive, when brought more fully into 
com^petition with the easitern fauna of the coastal region ; 
but they are still living farther south and west, within the 
Mississippi drainage area. It is also especially noteworthy 
that the very rapid evolution now in progress producing the 
exceedingly abundant species of insects is shown by the 
changes, or less probably the extinction, of nearly all the spe- 
cies of beetles found in the Scarboro' delta deposits. 
If all this history was subsef|uent to the beginning of the 
erosion of the Niagara river gorge, and previous to the rise 
of this western part of the glacial lake Iroquois, occasioned 
by the uplifting of the country including its outlet at the east, 
to form the upper Iroquois beach of Toronto and its vicinity, 
which I think probable, only a few hundred years, or perhaps 
a thousaSnd years, more or less, must have sufficed for the 
•deposition, of the Toronto and Scarboro' interglacial and 
■glacial series. This conclusion seems well consistent w'it'.i 
the apparent evidences of seasonal changes, as if marking 
years, which Coleman mentions as frequent in the Scarboro' 
peaty clays. 
EDITORIAL COMMENT. 
ANNOUNCEMENT OF THE THEORY OF EVOLUTION. 
There is no more notable event in the history of science 
than the joint presentation before the Linnean Society in 1858 
of papers by Charles Darwin and Alfred Wallace announcing 
the theory of evolution by natural selection. Darwin, as is 
generally known, was most careful in his methods of work. 
His theory in regard to the transmutation of species by natural 
selection was slowly thought out from the time of the voyage 
of iht' Beagle, and was put in writing in 1844. This manu- 
