REPORT OF TEE CHIEF ASTRONOMER 67 



SESSIONAL PAPER No. 25a 



quartzitic sandstone. All these rocks are very hard, and were it not for the 

 fissility incident to thin bedding, the formation would be exceptionally resistant 

 to the forces of weathering. 



The alternation of the quartzites and more argillaceous beds* 

 is so common and the graduation of the one rock-type into the other 

 is throughout so persistent that it has proved impossible to make a useful 

 minute subdivision of the formation. In the section at King Edward peak the 

 uppermost 200 feet are very thick-bedded and are composed chiefly of typical 

 quartzite. In the sections between Oil City and the north end of Waterton 

 lake at least 100 feet of blackish, red, and reddish gray shaly beds are inter- 

 bedded with the magnesian limestones and sandstones at the base of the forma- 

 tion. None of these types was noted in sections farther west, and, in its 

 lower part at least, the formation seems to become more dolomitic or more 

 ferruginous as it is followed eastward. Sun-cracks and ripple-marks, especially 

 the former, were seen at many horizons from top to bottom of the Appekunny. 

 No fossils have yet been found in it. 



Collecting all the information derived from the Boundary belt, a composite 

 columnar section of the formation as exposed in the Clarke range, has been 

 constructed and may be described in the form of the following tabic : — 



Columnar section of Appekunny formation. 

 Top, conformable base of the Grinnell formation. 



200 feet. — Thick-bedded quartzite with subordinate interbeds of gray and rusty metar- 

 gillite. 

 2,025 ' Light gray to rather dark gray (dominant) siKcious metargillite and quart- 

 zite, weathering gray and rusty-gray, thin-bedded; many relatively mas- 

 sive beds of whitish and rusty quartzite occur among the staple thin 

 beds of the rapidly alternating metargillite and quartzite; sun-cracks 

 and ripple-marks common. 

 75 " Thin to medium-bedded, buff-weathering silicious dolomite. 



300 ' Highly variegated, gray, green, reddish, and black metargillite and quart- 

 zite, weathering in tones of brown, red, and gray; a few intorbeds of 

 buff dolomitic sandstone and grit; sun-cracks and ripple-marks. 



2,600 feet. 



Base, conformable top of the Altyn formation. 



Thin sections of typical phases have been examined microscopically. They 

 revealed an even higher percentage of free quartz than was in the field sus- 

 pected to characterize the rock. This mineral occurs in very minute angular 

 individuals from 0-005 mm. or less to 0-03 mm. in diameter, with an average 

 diameter of about 0-01 mm. No certain trace of an originally clastic form was 

 anywhere observed. The quartz is intimately intermixed and interlocked with a 

 nearly colourless to pale-greenish mineral, which, on account of the extremely 

 small dimensions of its individuals, is difficult to determine. The single refrac- 

 tion is notably higher than that of quartz; the birefringence is apparently low 

 but, in reality, may be high, the common low polarization tints being due either 

 to the section's passing across the optic axes or to superposition of differently 



25a— 5J a 



