REPORT OF THE CHIEF ASTRONOMER 81 



SESSIONAL PAPER No. 25a 



no intercommunication either to the unaided eye or under the microscope. 

 The water from which the calcite was precipitated undoubtedly entered each 

 vesicle through openings in the walls but such openings must have been 

 generally of subcapillary size. It is difficult to imagine the play of forces or 

 the history of the crystallization which grouped the calcite molecules in one 

 amygdule so as to give its filling a common crystallographic axis with hundreds 

 of neighbouring amygdules. It looks as if the force of crystallization had oper- 

 ated directly through the rock wall of each vesicle. 



Kintla Formation. 



In the field the Kintla formation is a conspicuous element of the Lewis 

 series. Stratigraphically the highest known member of the series, the Kintla 

 commonly occurs on the higher summits and thus above tree-line. The fine 

 exposures and a striking deep red colour, contrasting 1 with the bright buff beds 

 of the Sheppard, render the argillite visible for many miles. Beautiful colour 

 effects in the rugged Lewis and Clarke ranges are controlled by the rich tints 

 of the argillite as it lie® in place on the mountain-crests or, by its streaming 

 talus, lends broad slashes of colour to the lower slopes. 



The best studied sections in the Boundary belt are both north of the 

 Boundary line; one at the head of Kintla creek canyon, the other at the head 

 of Starvation creek. The rocks in the former section have been described by 

 Willis, to whom we owe the name of the formation : — 



' The highest beds of the ancient sequence of strata found in this part 

 of the range are deep red argillaceous quartzites and silicious shales, with 

 marked white quartzites and occasional calcareous beds. They are named 

 the Kintla formation from their occurrence in mountains on the 49th 

 parallel, northeast of Upper Kintla lake. They also form conspicuous 

 peaks west of Little Kootna creek. The Kintla formation closely resembles 

 the Grinnell, and represents a recurrence of conditions favourable to 

 deposition of extremely muddy, ferruginous sediment. The presence of 

 casts of salt crystals is apparently significant of aridity, as the red char- 

 acter is of subaerial oxidation. The formation has an observed thickness 

 of 800 feet, but no overlying rocks were found. Its total thickness is not 

 known, and the series remains incomplete.'* 



To Willis' account the following details may be added for this section. 

 The basal member is sixty feet thick, consisting of red, sandy argillite inter- 

 stratified with thin beds of bright gray silicious and magnesian limestone and 

 magnesian quartzite, each type weathering buff. These interbeds are identical 

 in character with the principal phase of the Sheppard, showing that the two 

 formations are dovetailed together. Overlying these red beds is a forty-foot 

 flow of basic vesicular lava, lithologically similar to both the Purcell Lava and 



*B. Willis, Bull. Geol. Soc. America. Vol. 13, 1902, p. 324 

 25 a— 6 



