ON GEOLOGIC TIME-DIVISIONS 353 



would say that I am disposed to be very conservative and would 

 like to see as little disturbance as possible of terms that have 

 met with somewhat general acceptance. The terms, Group, System, 

 Series, Stage, and the correlative time-divisions, Era, Period, 

 Epoch, Age, are to my mind very satisfactory. Of course any 

 other terms would answer equally well provided geologists were 

 agreed to use them. What we need to do, as it seems to me, is 

 to adopt in this case the method that is in most general use, and 

 by extending the use of it to make it more and more general 

 until it becomes universally adopted. I would not like to see 

 the term For?natio?i used in place of Stage, and this simply for the 

 reason that Formation is now in use as a loose, general term. 

 Such a term is very much needed, and any attempt to change 

 Formatio?i from a loose to a precise term would be attended with 

 great confusion. Heaven knows we have confusion enough now 

 to contend with. 



It does not seem to me to do any harm to leave the Lower 

 Carboniferous or Mississippian as a division of the Carboniferous. 

 The use of the term Mississippian would be an advantage ; and 

 the arrangement I would prefer, simply as a result of my attitude 

 of conservatism, would give Mississippian the same rank as 

 Corniferous, Hamilton and Chemung in the stratigraphy of the 

 Devonian. 



The greater part of the assemblage of strata called Permian 

 by Prosser and the geologists of Kansas University contains pre- 

 cisely the same fauna as our Missourian or Upper Coal Measures, 

 and if there is no better excuse for recognizing Permian in 

 America than that afforded by the beds in question, then America 

 has no Permian. At all events if these strata are Permian then 

 the Permian cannot be separated from the Carboniferous. A 

 large percentage of the so-called Permian fauna occurs in the 

 coal-bearing strata of Indiana, Illinois and Iowa, that is, the fauna 

 actually begins in what we call in Iowa the Des Moines stage, or 

 Lower Coal Measures. Personally I see no good reason for 

 recognizing Permian in America, but if we must in order to keep 

 up with Europe, then the Permian must rank as a subdivision of 



