THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS. 21 



" I would also submit that neither a schistose nor a bedded structure can be 

 accepted as proof of a non-igneous or volcanic origin, and that a once mas- 

 sive lava-flow, whether augitic or feldspathic, is as likely, through pressure 

 and metamorphism, to assume a schistose structure as are ordinary sedi- 

 mentary strata. It is, I am aware, not in accordance with generally received 

 ideas on the nature of ancient igneous rocks to suppose they can be schistose 

 and stratified, especially so in America, where volcanic agency in the earlier 

 geological periods has been almost entirely ignored, and all those rocks 

 which by their microscopic characters and chemical composition, and by 

 their geological associations and relations, point to volcanic agency as the 

 cause of their formation, have been said to be ' not igneous, but metajnorphic 

 in origin,' a description which, it seems to me, is decidedly self-contradic- 

 tory." ^ 



Selwyn later again maintained his volcanic group, and pub- 

 lished microscopic descriptions of some of its rocks (quartz- 

 porphyry and porphyrite) by Adams.^ Little or nothing is added 

 to our knowledge of the strictly volcanic rocks by the two sub- 

 sequent reports on the geology of the Eastern Townships by 

 Ells.3 



The recognition of ancient volcanic rocks in the United 

 States is far behind that which prevails in Canada. This, as 

 has already been pointed out, is due to the influence of so-called 

 "metamorphic" ideas, or more properly to the Wernerian doc- 

 trine, that every rock showing any foliated or parallel structure 

 is sedimentary. 



New England. — Very little definite information can be gath- 

 ered from the earlier reports on the geology of Maine, by Jack- 

 son and C. H. Hitchcock, regarding the old volcanic deposits. 

 Jackson frequently uses such petrographical terms as "amygda- 

 loidal trap, ribbon jasper, clinkstone porphyry, and breccia com- 

 posed of an infinity of fragments of jasper," in describing the 

 rocks near Eastport and Machiasport, on the Maine coast. He 

 regarded the basic rocks (trap) as eruptive, but the "jasper" as 

 semifused sediments whose lines of stratification were still pre- 



' Trans. Roy. Soc. Canada, Vol. i, p. lo, 1882. 



= Report of the Geol. Survey of Canada, 1880-82, A. p. 2 and pp. 10-14. 



3 lb., 1886, J., and ib., 1887-88, K. 



