42 NEW YORK STATE MUSEUM 



the Committee on Geologic Names of the United States Geo- 

 logical Survey, which sent the following reply^ : 



The Committee on Geologic Names on May 12th took action 

 on the validity of the term Monroe in several publications of 

 1891, 1892. (1893), and 1895, as the name of a group of rocks 

 distinguished in southern Michigan, as against the standing of 

 the name published in 1894 for a shale formation in southeastern 

 New York. 



The committee recommended that the Monroe group of south- 

 ern Michigan should retain the name, and this action has been 

 approved for official publications of the geological survey. 



The conclusion was reached on the ground that priority and 

 prescription, or established usage, are combined in the Michigan 

 application of the term in such a way as to make its continued 

 use more desirable than that of Monroe shale in New York ; 

 but the case was not considered one in which priority was so 

 definitely obvious as to justify the conclusion on the ground of 

 the publication of 1891-92 (1893) only, since in that publication 

 the definition was inadequate. 



The CornwalP shales are well shown at Pea hill where they 

 have a thickness of at least 200 feet. They here appear as two 

 steep ridges, which seem to conform to the synclinal structure 

 of this area and form the highest points on the map east of the 

 Moodna river. These shales are dark gray in color and in places 

 a pronounced slaty cleavage is shown. The number of fossil 

 species found in them is small, but the number of individuals of 

 the same species is quite large. The best localities for collect- 

 ing are in the old vineyard and the woods on the south side of 

 the east cliff, and on the steep western face of the west cliff. 

 The fossils found are usually distorted and not well preserved- 

 Darton^ mentions a locality on the south side of Pea hill where 

 is an inconspicuous outcrop of fine grained red and gray sand- 

 stone in which the following genera were observed : 



1 Chonetes 5 Spirifer 



2 Meristella . 6 Tentaculites 



3 Orthis 7 Theca 



4 Rhynchonella 



Oriskany formation. So far as is known the Oriskany lies 

 directly below the Cornwall shales in Pea hill. The contact 

 between these formations at this place has not been observed, 

 so it is at present impossible to tell the exact nature of the rock 

 which directly overlies the Oriskany. In New Jersey, Kiimmel 



iGeol. Sur. Ohio. 1905. Ser. 4. Bui. 7, p. 26. 



2The expression Cornwall limestones has been used by Eckel to designate the limestones of 

 this area which in age range from the Decker Ferry to the New Scotland. He says, "the term 

 'Cornwall limestones' is not here proposed as a formation name, but is used merely as a con- 

 venient designation for the series till further field work shall have decided the extent to which; 

 subdivision can be carried." N. Y. State Geol. An. Rep't. 1900. p. ri48. 



3N. Y. State Geol. 15th An. Rep't. 1895. p. 417- 



