History of the Quebec Group. — Hunt, 223 
craft's mountain, near the town of Hudson, and other related 
cases, must not be forgotten. 
When geologists abandoning the hypothesis of Mather re- 
cognize the fact that in the area mapped by him and his 
disciples as belonging to the Hudson-River group, there exists 
a great development of more or less fossiliferous strata alike 
of Cambrian, of Ordovicianand,more rarely, of Silurian age, — 
that the Cambrian strata are greatly disturbed so that their real 
succession has been frequently misunderstood — and moreover 
that they are overlaid, unconformably by Ordovician strata, 
which were affected by later movements, and in the local ab- 
sence of the massive Trenton limestones are often confounded 
with the subjacent Cambrian, some of the confusion which 
now perplexes workers in that region will be removed. 
The weighty testimony of James Hall in this connection 
in 1862 should not be lost sight of. Referring to the evidence 
of organic remains then recently found in the Hudson- 
River slates in Vermont and Canada he remarks that they 
"prove conclusively that these slates are to a great extent of 
older date than the Trenton limestone'' adding that "the 
occurrence of well known forms of the second fauna — LeptoBna 
sericea, Orthis testudinaria, Asaphus (Isoielus) Trinucleus, 
etc. — in intimate relation with and apparently constituting a 
part of the series along the Hudson river, requires some 
explanation. Looking critically at the localities in the Hudson 
valley which yield these fossils we find them of limited and 
almost insignificant extent. Some of them are at the subq- 
mits of elevations Avhich are synclinal axes * * * * where 
the remains of newer formations would naturally occur. 
Others are apparently unconformable to the rocks below, or 
are entangled in folds of the strata, * * * * while the 
enormous thickness of beds exposed is almost destitute of 
fossils." The graptolites of the Hudson valley "which have 
hitherto been referred to the age of the other fossils found in 
the small outliers, or to the second fauna, in reality hold a 
lower position and belong to the great mass of slates below." 
Inasmuch then as the Hudson-River strata in their typical 
localities are, as a body, older than the Trenton limestone, 
which is itself older than the Loraine shales and the shales 
and sandstones of Pulaski "the term Hudson-River group can 
not be properly extended to these rocks, which on the west 
side of the Hudson are separated from the Hudson-River 
