Pleistocene. 



REPORT OF THE CHIEF ASTRONOMER 89 



SESSIONAL PAPER No. 25a 



For the purpose of this report, however, it will be expedient to reduce the sum- 

 mary of his findings to the table of formations given on page 315.* 



/"Eastern continental I Cnaracterize . d b y boulders of granitic, gneissoid, and other 

 ,v, Laurentide rocks ; formsamoraine across Saint Mary and 



^ Belly valleys and beyond. 



It Distinguished by absence of Laurentide rocks; composed of 

 Valley glacier drift. •] Algonkian sedimentary and igneous rocks in heterogeneous 



v. I association as till and stratified drift. 



f Type locality — a gravel mesa, elevation 5,800 feet, 5 miles 

 east of Chief mountain, north of Kennedy creek, and 900 

 feet above it ; characterized by water- worn material of local 

 Pleistocene Kennedy high level j origin, Algonkian rocks up to two feet in diameter ; average 



or Pliocene. gravels. coarse stuff under one foot, much of it 2 to 6 inches ; dist- 



inguished by absence of glacial striae, by stratification, and 

 L by altitude above present stream channels. 



The reader is referred to the fuller account of the Kennedy gravels, which 

 the present writer has not specially studied except on the line of a single tra- 

 verse. The view of Salisbury, quoted by Willis, that ' the high-level quartzite 

 gravels on the plains east of the mountains are believed to be deposits made 

 by streams at the close of the first epoch of baseleveling recorded in the pre- 

 sent topography,' seems to be scarcely supported by the evidence of the gravels 

 themselves, unless it is meant that uplift occurred at the close of the epoch. 

 It is highly improbable that wide-spread clastic material of such coarseness could 

 be formed during the closing stages of an erosion-cycle. 



STEUCTURE. 

 FOLDS AND FAULTS. 



On referring to map sheet No. 1, and especially to the general sec- 

 tion, it will be seen that the Clarke range forms a great syncline which 

 is accidented with a few faults and secondary warps. The eastern 

 limb of the master fold shows the entire succession of rocks from the 

 Waterton dolomite to the Kintla argillite. Every member of the Lewis series 

 is thus exposed, in its regular order, in the huge monocline stretching from the 

 elbow of Oil creek (Cameron Falls brook) to the summit lake at the head of 

 the creek. The dip slowly flattens from an angle of 30° in the Altyn formation 

 to approximate horizontality at the water-divide of the range. The western 

 limb of the syncline displays the complete series from the Kintla formation 

 down nearly to the base of the Appekunny formation. The dips in the lower 

 members there average about 20° to the northeast; those of the higher members, 

 between upper Kintla lake and the Great Divide range from 3° to 5° with 

 variable strike. 



At both sides of the master syncline the strata are rather sharply flexed 

 down. There results, on the east, the narrow Cameron Falls (Oil creek) anti- 

 cline, which plunges toward the northwest at a low angle. On the western 

 side the down-warped strata are very poorly exposed but it is probable that the 



* B. Willis, Bull. Geo!. Soc, America, Vol. 13, 1902. 



