AMERICAN GEOLOGY DECADE OF 1850—1859. 431 



Red sandstone. Still, if the Richmond coal basin is of the same age as the coal rocks 

 of North Carolina, geologists will be disposed to place the series along with the 

 Oolites or Lias, as Profs. W. B. Rogers and Sir Chas. Lyell have done." 



Emmons in this work rejected completely the old Wernerian classi- 

 fication of (1) Primitive, (2) Transition, and (3) Tertiary, and intro- 

 duced that given in tabular form below. It seems to have met with 

 little favor, and was not, so far as the present writer is aware, adopted 

 in a single instance elsewhere. 



EMMONS'S ROCK CLASSIFICATION, PROPOSED IX 1852. 



1. Pyrocrystalline — crystallized by the agency of tire. Primary of authors. 

 II. Pyroplastic — molded by tire. Ancient and modern volcanic rock of authors. 



III. Hydroplastic — molded by water. Sediments of authors. 



The first class is divided into two sections: 



1. I nstratitied pyrocrystalline, as granite, hypersthene rock, pyrocrystalline lime- 

 stone, sienite, magnetic iron ores. 



2. Stratified pyrocrystalline gneiss, mica slate, talcose slate, and hornblende 

 steatite. 



The second class is divided into two sections, also: 



1. Modern pyroplastic rocks, lavas, tuffs, pumice, and all the products of volcanoes, 

 which are cooled in the air. 



2. Ancient pyroplastic rocks, the ancient lavas, cooled under water, basalt, por- 

 phyry, and green stone. 



The third class is divided into systems, most of which are admitted 

 by geologists of this day. 



The systems belonging to the class of hydroplastic rocks, the con- 

 solidated and loose sediments, are exhibited in the following table: 



I. Tertiary system: 



1. Postpliocene. 



2. Pliocene. 

 3 Miocene. 

 4. P]ocene. 



II. Cretaceous system: 



1. Upper Cretaceous, including the. true chalk, with flints. 



2. Lower Cretaceous, including the green sand, iron sands, etc. 

 III. Wealdon, unknown in the United States. 



IV. Oolite and Lias. 



V. New Red Sandstone or Trias: 



1. Upper. 



2. Middle. 

 '.->. Lower. 



"At a meeting of the Boston Society of Natural History on January 4, 1854, Prof. 

 W. B. Rogers summed up the evidence regarding the red sandstone of Virginia and 

 North Carolina, and found it "to confirm the conclusion of their Jurassic date." 

 The fossils thus far formed in the more western red sandstone belt ami its extrusion 

 through Pennsylvania and New Jersey showed this also to be Jurassic, a little Lower 

 probably than that of Virginia and North Carolina. He felt that there was little 

 doubt but that the same conclusions would apply also to the sandstone of the Con- 

 necticut Valley. 



