70 DEPARTMENT OF THE INTERIOR 



2 GEORGE V, A. 1912 



The M /nation is admirably exposed' on the southwest side of King Edward 

 Peak, which overlooks the Flathead valley about three miles north of the 

 Boundary line. 



In this section the total thickness is 1,600 feet, distributed as follows : 



Columnar section of Grinnell formation. 



Top, conformable base of the Siyeh formation. 



355 feet. — Thin-bedded, red metargillite with intercalations of red, quartzitic sand- 

 stone. 

 20 " Flow of basic, amygdaloidal lava. 

 75 " Thin-bedded, red metargillite. 



100 ' Thick-bedded, gray metargiliitic quartzite, weathering light rusty brown. 

 1,050 " Thin-bedded, red to reddish gray metargillite and quartzitic sandstone. 



1,600 feet. 



Base, conformable top of the Appekunny formation. 



Sun-cracks and ripple-marks are common in all the sedimentary members. 

 In a section on Oil creek the ripples at one horizon measured from four to 

 twelve inches from crest to crest, indicating currents of great power, such as 

 the heavy tidal rips occurring in the Bay of Fundy and other estuaries of the 

 present day. If these ripples were caused by wind-wave current, the waves 

 must have been of very large dimensions. 



Under the microscope the sandstone specimens are seen to be composed 

 essentially of rounded quartz grains, averaging 0-25 mm. in diameter. Many 

 of the grains are secondarily enlarged and to such an extent that the rock has 

 the fracture and the strength of true quartzite. A small amount of amorphous, 

 apparently argillaceous matter, tinted with the red oxide of iron, forms the 

 rest of the cement. No feldspar was seen in this section. 



The metargillites are made up of a very compact mass of sericite, quartz, 

 chlorite, and abundant iron oxide. In one thin section minute crystals of a 

 pale brownish carbonate, probably dolomite, are distributed through the mass. 

 The carbonate seem also to be an original constituent and may have been 

 chemically precipitated along with the mechanically deposited mud, the domin- 

 ant original component of these beds. 



The specific gravity of a type specimen of the red quartzite is 2-678. The 

 specific gravities of two specimens of the metargillite are 2-740 and 2-757. The 

 average for the whole formation is about 2-725. 



The amygdaloid is a dark green-gray, compact rock, which both macroscopic- 

 ally and microscopically, is similar to non-porphyritic phases of the overlying 

 Purcell lava (described in chapter IX). It is much altered, but minute, thin 

 tabular crystals of labradorite with the same abundance and mutual arrange- 

 ment which this essential mineral has in the Purcell formation amygdaloid, still 

 represent the original microphenocrysts. The base was once glassy but is now 

 mainly composed of the usual secondary chlorite, quartz, and calcite. Numerous 

 small crystals of original ilmenite are now represented only by pseudomorphs of 



