38 SEDIMENTARY GROUPS OF THE PLATEAU PROVINCE. 



greatly distorting the facts. But a section thus arranged presents a series 

 of limestones, shales, sandstones and conglomerates totally unlike that 

 which has been established in the New York and Appalachian Province or 

 in the Valley of the Mississippi. Again in several of the groups we dis- 

 cover the remains o t f rich faunas and floras, but the series of fossils belonging 

 to any of the natural groups in the Plateau Province is unlike that of any 

 group or formation in the earlier studied rocks of the east ; either entirely 

 new series are found or the old types are regrouped so as to present a new 

 aspect. Hence it would be manifestly absurd to introduce into this newly 

 studied province the nomenclature adopted in those provinces which had 

 been previously studied, as it would involve the necessity of explaining in 

 each case that the name was used with a new meaning, and that the adop- 

 tion of the older names was intended simply to express the opinion that the 

 group to which it was given should be referred to some period in the geo- 

 logical time scale about the same as that held by the group to which the 

 name was originally applied ; and this would involve the re-adjustment of 

 the names from time to time on the collection of new suites of fossils. While 

 it does not seem possible to consider a particular sandstone or limestone, or 

 a particular group of strata as identical with or closely similar to one in 

 New York or Illinois, this does not preclude the possibility of establishing a 

 general synchronism. The Cenozoic, Mesozoic and Paleozoic Ages seem 

 to l)e as well defined as elsewhere, and in each age there are formations 

 which are earlier or later, but the details of this general synchronism can 

 only be discovered after a far more thorough study of the paleontology of 

 the province has been made. 



The conclusions thus stated have been reached after a stud}' of the 

 province which ' has occupied the greater part of the last eight years. 

 During the earlier years I attempted here to find the formations of the 

 east, or at least formations corresponding to them, and thus years of study 

 were in part fruitless for that reason. I then determined if possible 

 to discover the natural series of the province itself independent of 

 other regions, and the general section below is the result. Perhaps, from 

 a priori reasons, I should have commenced with this plan. The supposi- 

 tion that at the same time sediments should have been carried into the 



