THE BRIAN OR DEVONIAN FORESTS. 



107 



In order that distinct notions may be conveyed as to the geo- 

 logical horizons of the species, I may state that the typical Devonian 

 or Brian scries of Canada and New York may Iw divided in descend- 

 ing order into — 1. T':e Chemung group, including the Chemung and 

 Portage sandstones and shales. 2. The Hamilton group, including 

 the Genesee, Hamilton, and IMarcellus shales. 3. The Corniferous 

 limestone and its associated beds. 4. The Oriskany sandstone. As 

 the Corniferous limestone, which is the equivalent of the Lower 

 Carboniferous limestone in the Carboniferous period, is marine, and 

 affords scarcely any plants, we may, as is usually done for like pur- 

 poses in the Carboniferous, group it with the Oriskany under the 

 name Lower Erian. The Hamilton rocks will then be Middle Erian, 

 and the Chemung group Upper Erian. In the present state of our 

 knowledge, the series may be co-ordinated with the rocks of Gaspe, 

 New Brunswick, and Maine, as in the following table : 



It may be proper, before closing this note, to state the reasons 

 which have induced me to suggest in the following pages the use of 

 the term " Erian," as equivalent to " Devonian," for the great sys- 

 tem of formations intervening between the Upper Silurian and the 

 Lower Carboniferous in America. 1 have been induced to adopt 

 this course by the following considerations: 1. The great area of 





1 : 





