1881.] Geology and Paleontology. 495 
tained by Emmons, whose Taconic system, as first proposed, was 
later declared by him to consist of an upper division, which he re- 
ferred to the horizon of the calciferous sandrock of the New York 
system, and a lower division, the proper Taconic. In this latter 
was included a great group of quartzites, limestones, and soft 
crystalline schists, which have since, by different geologists, been 
assigned to not less than three distinct horizons in the New York 
system. The grounds of those contradictory opinions have been 
supposed stratigraphical relations, and also the apparent associa- 
tion with the Taconic limestones of organic remains belonging to 
these various horizons. 
In localities away from the disturbed regions of the Appala- 
chian valley there exists a series of rocks occupying the position 
assigned by Emmons to his Lower Taconic, and agreeing with 
this in its essential characters. Such a series is found north-west 
of the Appalachian region, a little to the north of Lake Ontario, 
Where it rests upon schists like those of the Green mountains, 
and is unconformably overlaid by the Trenton limestone, an 
] 
_ Again, Mr. W. O. Crosby has lately described a similar series 
in the Island of Trinidad, resting on the ancient crystalline rocks 
and overlaid unconformably by limestones of Trenton age. 
We have thus abundant evidence of a great and wide-spread 
Series of rocks, pre-Cambrian in age, and occupying the position 
assigned by Emmons to the Lower Taconic or Taconian system 
—which, according to him, extends continously along the Appa- 
Within the vast region occupied by these rocks in the great 
valley, have been found a few small areas of fossiliferous strata, 
belonging chiefly to the Ordovian (Siluro-Cambrian) or to the 
mbrian series; but the characters of the great mass o these 
rocks are such as to lead to the conclusion that they constitute, 
aS Maintained by Emmons, a more ancient series. ae 
To the Taconian rocks belong the peculiar magnetic iron-ores 
found at Reading, Cornwall, and Dillsburg, Penn., which have 
n by some geologists regarded as Mesozoic, but were by 
Rogers assigned to the base of the Paleozoic. To this same 
