16 KENTUCKY GEOLOGICAL SURVEY. 



Nomenclature and Notes on the Table. 



ORDOVICIAN. The term Ordovician was introduced by Lap- 

 worth in 1870 for what is known as the Lower Silurian, but by 

 some called Upper Cambrian. To escape the ambiguity thereby 

 caused, as to whether in any given case Lower Silurian means 

 the lower part of the whole Silurian, or of the Silurian proper, 

 i. e., Upper Silurian, the term Ordovician is now generally used 

 for the system before known as Lower Silurian. 



CINCINNATI AN. In the early days of geological correlation, 

 the Blue Limestone, as the Cincinnatian series was at first de- 

 signated, was supposed to be the western equivalent of the Hud- 

 son river group of New York. Later Newberry and Orton, in 

 the reports of the Ohio Geological Survey, considering it to have 

 a irommingling of both the Trenton and Hudson river faunas 

 (an error), discarded the name Hudson river group for the Blue 

 Limestone in favor of the name Cincinnati group, shortly be- 

 fore proposed by Meek and Worthen. It has now been conclu- 

 sively shown that the Hudson river group along the Hudson 

 river, its typical area, contains Trenton and other metamor- 

 phosed formations. Hence doubt has arisen whether the name 

 can be retained at all. By common consent the name Cincin- 

 nati or Cincinnatian has been adopted for the series of forma- 

 tions of upper Ordovician age in the Ohio valley. 



RICHMOND. The term Richmond is applied to the higher 

 formations of the Cincinnatian. It is followed by the Clinton 

 limestone belonging to the Silurian system. In New York, be- 

 low the Clinton are found the Medina sandstone and the Oneida 

 conglomerate, which are always placed in the Silurian; but no 

 Richmond has been reported. The conclusion seems inevitable 

 that either there is a hiatus at this point in one or the other 

 province, or that the New York Medina and Oneida and the 

 Ohio Valley Richmond are synchronous. 



SALUDA AND AKNHEIM. Within the past few years it has 



