Geology of Cincinnati. 2 1 



worthily applied ; for, although rocks of the same age are found 

 in othe"- states and other localities in Ohio than about Cincinnati, 

 yet it is here that they are best exposed ; here where most of the 

 work has been done, and the name of Cincinnati Croup will be 

 adopted in this paper.* 



But leaving this to be discussed by others, let us proceed with 

 the subject in hand. No matter what name may be given to the 

 particular group, no one is prepared to deny that it belongs to that 

 great series of sedimentary strata known as the Lower Silurian. 

 Rocks having the same general characters, and often with the 

 same varieties of animal life, are exposed to the east as far as 

 Waynesville, to the north as far as Dayton, and on the west to 

 Madison, Indiana, reappearing in places in Illinois, \yhile to the 

 south it extends to near Frankfort, Kentucky, reappearing at 

 Nashville, Tennessee. 



Like all other fossil-bearing rocks, those of the Cincinnati 

 Group are sedimentary in their origin, and were originally de- 

 rived from the wearing away of lands either near or remote. In 

 the present instance, all the sediment was derived from high 

 mountains which existed far north of Lake Erie, forming part of 

 the ancient. Archean Continent. At this time there stretched a 

 deep sea ove> the earth south of the 45 deg. of north latitude, and 

 upon the floor of this ocean the sediment from the Canadian 

 mountains was deposited in immense sheets, aggregating more 

 than six thousand feet, and filled with a most wonderful profusion 

 of animal remains. 



The period of time required for the deposition of this sedi- 

 ment was immense, and is not to be readily calculated. But the 

 time at last came when certain elevatory forces began to act, and 

 there was at last raised above the sea level an island, extending 

 from somewhere near the center of western Ohio, south to the 

 center of Kentucky, while near the same time large tracts ap- 

 peared above the water in northern and eastern New York, in 

 Wisconsin, Illinois, Minnesota, and small outlyers in Missouri, 

 Arkansas and Tennessee. 



*It may be well to state that some years ago (See this Journal, vol. i, p. 193I cer- 

 tain of the geologists and collectors of Cincinnati presented a report to this Society rec- 

 ommending that the term, "Cincinnati Group," be discarded in favor of that of "Hud- 

 son River Group." But since that time some of these gentlemen have reconsidered 

 their action, and now recognize the term "Cincinnati" as more appropriate. It may be 

 said that the majority of Western geologists recognize the term "Cincinnati," while 

 the majority of Eastern geologists adhere to "Hudson River" and "Utica Slate." 



