X INTRODUCTION. 



above, we proposed for this formation the name Kinderhook 

 group, from its development at the village of that name in Pike 

 county, of this State — stating, at the same time, that we could 

 no longer view it as the equivalent of the Chemung, and that 

 we regarded it as being more intimately related to the Carbon- 

 iferous above, than to the Devonian below. It is proper that we 

 should state here, that this opinion was also previously main- 

 tained by M. de Verneuil, Dr. Norwood and Dr. Owen, as well 

 as some others. 



At the time we proposed the name Kinderhook group for 

 this formation, little was known in regard to its relations to 

 some similar deposits Prof. Winchell had called the Marshall 

 group, in Michigan, and to what the Ohio geologists had desig- 

 nated as the Waverly sandstone, in Ohio. Since then, however, 

 we have traced this rock into Northern Ohio, and ascertained, 

 beyond doubt, that it is the same as the Waverly sandstone, or 

 at any rate, as the only portion (the upper part) of that series 

 in which we succeeded in finding fossils. Prof. Winchell, who 

 concurs in the opinion that these beds belong to the Carbonif- 

 erous, has also since identified his Marshall group with the 

 Waverly sandstone. It is therefore probable that the oldest 

 name — Waverly sandstone, or more properly, Waverly group — 

 will have to be adopted for this formation. Until all questions 

 in regard to the exact parallelism of these deposits, as developed 

 in the several States alluded to, can be cleared up, however, by 

 farther investigations, it will be better to retain the local names 

 by which they are now known in the States mentioned. 



In the first volume of this Report, just published, on the 

 general geology of Illinois, the name " Clear creek limestone" 

 was provisionally used for a series of strata holding a position, 

 in Union and some of the adjoining southern counties, between 

 the so-called Hudson river group of the Lower Silurian, and a 

 Devonian sandstone that had been identified with the Oriskany 

 sandstone of New York. Formerly, when only a few imper- 



