1888 .] 
71 
[Marcou. 
characteristic fossils, as they are found at Trenton Falls and at 
Utica in New York. Its lithology also is the same as that of the 
formation in New York state. By Trenton group, I mean all the 
strata from the lowest bed of the Calciferous to the top of the Tren- 
ton, for the deposits in that narrow sea of the actual valley of the 
St. Lawrence have all the characters of a littoral formation, with 
local variations, more or less, limited to small areas. At St. Am- 
broise and even at a part of the top of Montmorency Falls, there are 
about twenty feet of sandstone and conglomerate, which have been 
referred to the Potsdam without any palaeontological proofs, and 
which very likely represent there the Caleiferous-Chazy. After we 
pass Industry and the Chicot Creek in Joliette and Berthier coun- 
ties, it is impossible to recognize the Calciferous and Chazy with 
the normal characters which they bear in the village of Chazy. 
They may be represented by the most inferior part of the almost 
horizontal strata of what is called Trenton, or those twenty feet of 
sandstone and conglomerate, or they may not have any representa- 
tives at all. However, at the Mingan islands, the Calciferous-Chazy 
seems to exist with a thickness of almost 500 feet ; although it is 
not certain that those strata of the Mingan represent either the 
Calciferous or the Chazy, being so different lithologically and even 
palseontologically. They may represent the whole lower and mid- 
dle divisions of the Champlain system. 
That narrow and very long Champlain band lies to the north over 
the primitive and crystalline rocks, and to the south on the strongly 
uplieaved and broken Taconic slates. Erosion and denudation, con- 
tinued without interruption from the time of their upheaval above 
the sea until now, have reduced them to extremely limited dimen- 
sions. Near their contact with the Taconic slates, landslides have 
often occurred ; and some patches of Trenton limestone are seen 
hanging down, almost at a perpendicular angle, on asperities of the 
primitive rocks, or inclosed in gorges and gullies ; and also some 
tongues of Utica slates have slipped over the Citadel hill slates of 
the upper Taconic and are found now and then, but always close 
by the normal line of Champlain outcrops. For such examples of 
landslides, I shall refer to the Montmorency Falls and its vicinity, 
and that at the foot of the lowest fall of the river Ste. Anne near 
the mouth of the river a la Rose. 
Directly south of the narrow band of almost horizontal Cham- 
plain system, we have an enormous thickness of strongly elevated, 
