14 THE JOURNAL OF GEOLOGY. 



It is the purpose of the writer in the present paper to main- 

 tain that in the great crystalline belt of eastern North America, large 

 areas of volcanic rocks occur, and that these, in spite of their great 

 age, are in all respects the same as modern volca?dc materials, save 

 for alterations subsequent to their original formatio?i — amo?ig which 

 alter atio7is devitrification has bee?i one of the most important} 



DISTRIBUTION OF VOLCANIC AREAS ALONG EASTERN NORTH 



AMERICA. 



I shall now proceed to summarize the present state of our 

 knowledge of these volcanic areas, as far as they belong to the 

 Eastern or Appalachian crystalline belt, omitting all reference 

 to the central Canadian, Lake Superior, Missouri, or other more 

 western regions of similar nature. In this review I shall com- 

 mence with Newfoundland and follow them southwest, parallel 

 to the coast. 



Eastern Canada. — In a recent comparison between the Eozoic 

 and Paleozoic rocks of eastern America and western Europe, 

 Sir William Dawson says that the Huronian was evidently a 

 coarse marginal deposit, accompanied by abundant volcanic out- 

 breaks, similar to those which occurred about the same time in 

 Wales. He is also confident that many of the bedded Huronian 

 rocks are really of volcanic origin, being ashes in an altered state. ^ 

 In the same paper he mentions volcanic rocks, both lavas and pyro- 

 clastics, as abundant in the Ordivician and Silurian formations 

 of eastern Canada. 



The reports of the Canadian and Newfoundland surveys 

 abound in references to rocks of a volcanic character in the 

 early Paleozoic and pre-Paleozoic horizons. These references 

 are, however, always purely those of a field-geologist engaged 

 in a rapid reconnaissance. The frequent use of such field terms 

 as felsite, porphyry, trap, amygdaloid, agglomerate, breccia and 

 ash suggest a vast development of contemporaneous volcanic 



^ On the nomenclature of these ancient and devitrified lavas, see Miss Florence 

 Bascom's paper, this Journal, Vol. L, No. 8, p. 825, Nov.-Dec. 1893. 



= Quart. Jour. Geol. See, Vol. 44, p. 801, 1888. 



