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THE DISTRIBUTION OF ANCIENT VOLCANIC ROCKS.
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"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 massive lava-flow, whether augitic or feldspathic, is as likely, through pressure and metamorphism, to assume a schistose structure as are ordinary sedimentary 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 metamorphic in origin,' a description which, it seems to me, is decidedly self-contradictory."[1]

Selwyn later again maintained his volcanic group, and published microscopic descriptions of some of its rocks (quartz-porphyry and porphyrite) by Adams.[2] Little or nothing is added to our knowledge of the strictly volcanic rocks by the two subsequent 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 doctrine, that every rock showing any foliated or parallel structure is sedimentary.

New England.—Very little definite information can be gathered from the earlier reports on the geology of Maine, by Jackson and C. H. Hitchcock, regarding the old volcanic deposits. Jackson frequently uses such petrographical terms as "amygdaloidal trap, ribbon jasper, clinkstone porphyry, and breccia composed 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-

  1. ↑ Trans. Roy. Soc. Canada, Vol. 1, p. 10, 1882.
  2. ↑ Report of the Geol. Survey of Canada, 1880-82, A. p. 2 and pp. 10-14.
  3. ↑ Ib., 1886, J., and ib., 1887-88, K.
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