REPORT OF THE CHIEF ASTRONOMER 179 



SESSIONAL PAPER No. 25a 



Correlation with the Belt Terrane * 



Earlier Views on the Belt Terrane. — To one acquainted with the geological 

 literature of the Cordillera, the writer's foregoing correlation is obviously quite- 

 different from that adopted by the United States Geological Survey for these 

 old formations as exposed in the United States. By the present official views of 

 that survey, (1) the whole of the Belt Mountains series which underlies the 

 Flathead sandstone (the Belt terrane) is referred to the pre-Cambrian (pre- 

 Olenellns) or latest ' Algonkian ' ; and (2) the whole of the Lewis series as 

 described by Willis is considered as belonging to the same terrane and to the 

 same age. 



A brief history of the explorations on which these conclusions are based,, 

 is given by Walcott in his paper on 'Pre-Cambrian Fossiliferous Formations.'t 

 To facilitate the present discussion it is advisable to review the history at 

 least so far as to show the divergence of views on the correlation. 



In 1875 Dawson had incorrectly referred the Siyeh formation to the 

 Carboniferous, but later he stated the possibility that the Siyeh limestone is 

 the equivalent of McConnell's Castle Mountain limestone. He referred all the 

 underlying formations as far as the tipper Altyn, to the Cambrian.:}; 



In 1883 Davis made several sections through the Belt terrane rocks and 

 referred them provisionally to the Lower Cambrian, though without fossil 

 evidence.§ 



The next year Peale sectioned 2,300 feet of the terrane, then called the 

 East Gallatin group, and, referred the whole series to the Cambrian.** 



In 1893 he published a second account of the terrane, calling it the ' Belt 

 formation.' A significant paragraph may be quoted: 



' There is no doubt that after the Belt formation was deposited there 

 was an orographic movement by which the Archean area of nearly the 

 entire region represented on our map south of the Gallatin and Three 

 Forks was submerged just prior to the beginning of the Cambrian, before 

 the Flathead quartzite was deposited. Whether this movement occurred 

 immediately after the laying down of the Belt beds or after an interval 

 is of course the question to be decided, and the decision cannot be posi- 

 tively reached with the meagre data now at hand. I am inclined to think 

 that the subsidence of the Archean continent (or possibly islands) began 

 with the first accumulation of the sediments that formed the lower portion 

 of these beds and was coincident with their deposition throughout the 



* Recently Walcott has used the adjective "Beltian," a systemic form, to designate- 

 the " Belt terrane " of earlier publications. (C. D. Walcott, Smithsonian Misc. Col- 

 lections, Vol. 53, 1908, p. 169). 



fC. D. Walcott, Bull. Geol. Soc. America. Vol. 10, 1899, p. 201. 



X G. M. Dawson, Report on the Geology and Resources of the Region in the 

 vicinity of the Forty-ninth Parallel, 1875, p. 74; Bull. Geol. Soc. America, Vol. 12, 1901, 

 p. 68; cf. Ann. Report, Geol. Surv. of Canada for 1885, p. 39B and 50-51B. 



§ W. M. Davis, Tenth Census report, Vol. 15 on Mining Industries, 1886, pp. 697- 

 702. 



**A. C. Peale, 6th Ann. Report, U.S. Geol. Surv., 1885, p. 50. 

 25a— vol. ii— 121 



