356 The American Geologist. June, 1896 
These terrace formations are of very recent age and mantle 
over the trace of the San Bruno fault which dislocated the 
Merced series. Since the culmination of the general uplift 
subsidence to the extent of several hundred feet has ensued, 
as has been more fully described in a former paper.* 
University of California, March 31st, 1895. 
[Crucial points in the geology of the Lake Superior region. No. 4.] 
CANADIAN LOCALITIES OF THE TACONIC ERUP- 
TIVES. 
By N. H. Winchell. Minneapolis, Minn. 
It is well known that under the name Hudson River group, 
and later under the term Quebec group, the rocks of the Taconic 
system were extensively traced out in Canada, between the 
Vermont state line and the St. Lawrence river. In general 
they pass through the "eastern townships." If we neglect the 
early Canadian classifications, which were vague and largely 
haphazard and have been abandoned, we find Dr. Selwyn, in 
1877, clearly describing these rocks and assigning them a 
stratigraphic position between the Silurian and Laurentian,! 
*. e., to the position of the typical or original Huronian, and 
their age as "probably Lower Cambrian.'" In this description 
he refers to the same position various eruptives with which 
the clastic rocks are intimately associated. Dr. Selwyn may 
be considered one of the first of American geologists who dis- 
tinctly apprehended and stated the eruptive nature of these 
rocks. They had been regarded as "altered Quebec" rocks, 
and as such Sir William Logan extended the Quebec group 
over them, and elsewhere included a great range of basic erup- 
tives. On his great Canadian geological map, 1866, the 
Quebec group extends along the northwestern side of lake 
Superior. It embraces what is now known as the Animikie 
and Keweenawan. But Selwyn effected a great revolution in 
this classification. He rejected the Quebec group entirely, and 
separated the rocks that had been so mapped and described 
into several systems. Unlike Logan, he saw also the alliance 
* Bull. Dept. Gcol. Univ. Cal., vol. i, no. 8. 
fGeological Survey of Canada, Rep. of Prog., 1877-78. Report A, pp. 
3-1.5. 
