lesquereux.] EVIDENCE OF AGE OF LIGNITIC GROUP. 283 



these researches have demonstrated thepossibleidentification of the coal- 

 strata, a fact whose application, however, can become valuable to coal- 

 mining when we have more positive knowledge on the geographical and 

 stratigraphical distribution of the plants of the American Coal-Meas- 

 ures. 



In the Permian, as far at least as this formation is known by the ex- 

 posure of its rocks in Iowa, Nebraska, and Kansas, near the junction of 

 the Platte with the Missouri River, the records of vegetable paleontology- 

 are blank indeed ; for the sufficient reason that this formation is repre- 

 sented there only by niagnesian limestone or marine rocks whose only 

 fossil remains are invertebrate animals, the so-called Permo-Carbonife- 

 rous species, most of them indifferently referable to Carboniferous or to 

 Permian. But sandstone rocks have been observed in the Rocky Mount- 

 ains, which, without any animal remains, have been, from the nature of 

 their composition and from their superposition to old Paleozoic strata, 

 considered as referable either to the Carboniferous or to the Per- 

 mian. A few fragments of Calamites only, found in connection with 

 this formation and sent for determination, were sufficient to estab- 

 lish its relation to the Permian, for the Calamites represented by these 

 specimens, G. gigas, is a leading plant of the Lower Permian. This case 

 was recently repeated from a locality far distant from the former, and 

 the same reference equally established from a few specimens only. It 

 cannot be said in this case, as for the Carboniferous, that the general 

 characters of the plants are ivell known, and that therefore vegetable 

 remains of this formation may be used sometimes for determination, when 

 topography and animal paleontology cannot be taken as guides; for, to my 

 knowledge, the a'bove-mentioned specimens are the first vegetable re- 

 mains discovered as yet from American Permian rocks. 



For the Trias, the evidence supplied by vegetable paleontology is pre- 

 sented in opposition to that derived from animal remains, by one of the 

 highest geological authorities of this country. This formation, exposed 

 in North Carolina, and in Virginia near Richmond, also, has important 

 deposits of coal, whose age has been for a long time in discussion among 

 geologists, and has been definitively fixed by the remains of fossil plants 

 found in connection with them. In the last work published by Emmons, 

 American Geology, Part VI, the lower part of the section of page 17, 

 headed Permian, is described as the Chatam series, and its fossils, a few 

 fucoidal remains of uncertain affinity and a large number of animal re- 

 maius, crustacean, mollusks, fishes, saurians, are not considered as suffi- 

 cient to authorize a decision upon the age of the formation, whichis there- 

 fore left as uncertain. The upper part of the measure, however, has in 

 its divisions layers of shales, with plants, and though remains of animals 

 are not found in connection with this series, it is positively determined 

 as Triassic by the author, from vegetable paleontological evidence 

 only. The characters of the plants, as indicated especially by the 

 Cycadew, relate this flora to the -Jurassic of Europe; hence its appella- 

 tion of Triasso-Jurassic, given to the formation. I say the Jurassic of 

 Europe, for indeed this formation is as yet so indefinite in this country 

 that it has no records of any kind which may be used as points of com- 

 parison. Its flora is totally unknown ; and even if we had a few vegeta- 

 ble remains obtained from the strata considered as Jurassic in the Black 

 Hills, the Uinta Mountains and the Sierra Nevada, it is very question- 

 able if they could be used for identification of the formation. The Ju- 

 rassic, even for Europe, is the dark age of vegetable paleontology. Ex- 

 cept the oolitic coal deposits of England, its strata of enormous thickness 



