16 



TJtica Slate and 



This gives a distinct palseontological horizon of twenty-one species 

 in fourteen genera without the addition of the graptolites and Triar- 

 thrus JBecki. Fifty-four species distributed in twenty-three genera, 

 should sufficiently establish the palaeontological record of the Utica 

 slate as a distinct formation. 



In the Science Neios of March 15th 1877, Prof. C. H. Hitchcock, 

 in an article under the title " Lorraine Group, " reviews the nomen- 

 clature of the strata composing the Trenton series or Trenton period. 



"The proposition to substitute Cincinnati period for the term 

 Trenton period is one that increases the confusion which is con- 

 nected with the name Cincinnati." 



As Prof. Hitchcock admits the presence of the Utica slate horizon 

 at Cincinnati, he does away w4th the last reason for retaining the 

 term Cincinnati, as applied to any group, epoch or period oi Lower 

 Silurian rocks. On page 153, he says : ^ 



" The majority of the official board of Xew York geologists agreed 

 that the name Hudson River should be applied to all the slaty and 

 gritty rocks lying in the Hudson valley from the Highlands to Lake 

 Champlain ; while their jointly published map adds the synonomy 

 of Lorraine." 



In the Report of the First Geological District, Prof. Wm. H. 

 Mather says, p. 380 : 



"We have thus far described some of the characters and phen- 

 omena of the Hudson River rocks, on the right bank of the Hudson, 

 and have kept them distinct from those of the left bank, because 

 they are much more deranged on the east side of the river, by sev- 

 eral fractures and lines of upheave parallel to the main axis, extend- 

 ing north and south, and also by transverse fractures and lines of 

 upheave, that have deranged all the rocks of the Champlain divi- 

 sion, and packed them together, helter-skelter, in the utmost con- 

 fusion. They are contorted, broken and wrinkled, in almost every 

 conceivable manner, in the vicinity of the intersections of these frac- 

 tures and axes of disturbance; and although the lines of bearing 

 and dip of the strata are nearly uniform in their direction * * * *j 

 except near the intersections of the fractures and axes of disturb- 

 ance, yet the repetitions of the same strata so variously, with others 

 lying higher and lower in the geological series, and with frequent 

 apparent inversions of the order of superposition, renders it almost 

 impossible to determine from an examination of the strata on the 

 eo,st bank of tlie Hudson, what the real order of superposition is. 

 ****** Fortunately, nearly all the strata of the Champlain 

 division are exposed in the valley of the Mohawk, unchanged in 

 position and in some places along the west side oi the main axis 

 they may be examined in the order of superposition indicated in the 

 tabular arrangement of the rocks of that division." 



Prof, Mather was the geologist in whose district the strata in 



