820 THE JOURNAL OF GEOLOGY. 
Wadsworth? has also described basic volcanics from Newfound- 
land, and Walcott? has mentioned their occurrence in the Algon- 
kian of the Grand Canyon series, stating that according to 
Iddings’ examination they are true doleritic basalts.3 
The volcanics of the Michigamme district can be closely 
paralleled with similar rocks in Finland and Sweden, described 
in detail with full recognition of their volcanic origin by J. J. 
Sederholm ‘4 and by Otto Nordenskjéld.5 
Numerous descriptions of such occurrences have appeared 
within the past years from the English geologists,° and all of 
them have recognized in full their identity with the younger vol- 
canics, and have usually applied the names in use for the younger 
to their older equivalents. Wadsworth? was the first in America 
to follow and advocate this simplification of the nomenclature. 
In 1892, Williams’® article upon the South Mountain Volcanics 
appeared. 
In all other countries the generally accepted nomenclature 
has been a dual one, one term for a pre-Tertiary rock and another 
* Notes on the Rocks and Ore Deposits in the Vicinity of Notre Dame Bay, New- 
foundland. Am. Jour. Sci., 3d Ser., Vol. XXXIII., pp. 94-104. 1884. 
2 Algonkian Rocks of the Grand Canyon of the Colorado. Jour. GEOL., Vol. III.. 
No. 3, p. 325, April-May, 1895. 
3 Loc. cit., p. 330. 
4Studien tuber Archzische Eruptivgesteine aus dem Siidwestlischen Finland, 
Tsch. Min. and Pet., Mitt. XII., pp. 98-142. 18091. 
5 Uber Basische Ergussgesteine aus dem Elfdalener Porphyrgebiet. Bull. Geol. 
Inst. Univ. of Upsala, Vol. I., No. 2, pp. 105-112. 1893. Uber Archzeische Erguss- 
gesteine aus Smaland. Ibid., pp. 133-255. 
6 For references to their papers see GEIKIE: Anniversary Address, OW AGass 
Vols. 47 and 48,1891-2. Most of their papers are to be found in the files of the Q. 
J. G. S. and Geol. Mag. and Memoirs of Geol. Sur. of Great Britain. 
7 Notes on the Min. and Pet. of Boston and Vicinity. Proc. Bos. Soc. Nat. Bs 
Vol. 19, p. 236, 1877; ibid. 1878, pp. 309— 316. 
On the Classification of Rocks. Bull. Mus. Comp. Zool., Vol. V., No. 13, pp. 
275-287. 1879. : 
Geol. of the Iron and Copper Districts. Bull. Mus. Comp. Zool., Vol. VII., Geol. 
Ser., No. I, p. 157, 1880. 
Prel. Descr. of the Peridotites, Gannros Debases, andl Andesites of Minn, Geol. 
and Nat. Hist. Sur. of Minn., Bull. No. 2, 1887. 
a Am. Jour. Scr, 3d Ser., Vol. XLIV., p..486. 1892. 
