REPORT OF THE CHIEF ASTRONOMER 155 



SESSIONAL PAPER No. 25a 



The specific gravity of the conglomerate averages about 2-700; that of the 

 quartzite and metargillite 2-670, and that of the whole formation about 2-675. 



Kipple Formation. 



Wherever the Dewdney formation crops out within the Boundary belt, 

 it is conformably overlain by a heavily bedded mass of white quartzite which 

 forms the summit of Mt. Ripple and has therefore been named the Ripple 

 formation. Three complete sections were measured on as many ridge-summits 

 lying between Wolf creek and the Boundary line. The whole massive formation 

 is unusually resistant to the weather and its vertical strata compose some of 

 the highest summits in the region; such outcrops are very favourable to study. 

 The thickness seems to remain fairly constant at all the localities examined, 

 the average of the measurements giving 1,650 feet as the most probable value 

 for this region. 



The Ripple formation consists of a remarkably uniform, hard, very heavily 

 plated quartzite, breaking with a sonorous metallic ring under the hammer. 

 There are practically no interbeds of other material. The dominant colour of 

 the rock is white, but flesh-pink and light yellowish tones are common. The 

 general colour of the weathered surfaces, including joints, is a bright buff- 

 yellow which is characteristically decolourized to snow-white through the agency 

 of lichens and other plants. The effects of these colours among the extensive 

 felsenmeers above the forest-cap are as beautiful as they are striking. (Plates 

 17, 18 and, 71 B.) 



A principal feature of the quartzite is the occurrence of extremely well- 

 preserved ripple-marks at various horizons. On Mt. Ripple itself these mark- 

 ings are exposed in a truly spectacular fashion. In bed after bed for a thick- 

 ness of several hundred feet together the surfaces of the old sand were moulded 

 into typical ripples of highly varied orientation (Plate 18). As exposed on 

 bedding-planes these marks are to-day apparently as sharply marked as they 

 were when each bed was just covered by the next wash of sand. Whole cliffs 

 are ornamented with the strong ridges and troughs of the ripples themselves 

 or with their negative impressions. Occasionally a slab of the frost-riven rock 

 shows the compound ripple pattern of pits and mounds where the same sand 

 layer was subject to two succeeding currents setting from different directions. 

 Sometimes the quartzite is fissile along the planes of such rippled beds, only a 

 centimetre or so thick, but as a rule, the rock breaks out in large, massively 

 constructed slabs a half metre to a metre or more in thickness. In the task of 

 reducing the peaks formed of thi3 stubborn rock, the frost uses joint-planes 

 rather than bedding-planes. (Plates 70, B and 71, B.) 



The quartzite is extremely simple in composition. Under the microscope it 

 is seen to be essentially made up of sub angular, or much more rarely, rounded 

 grains of glassy quartz from 0-1 to 0-4 mm. in diameter. These are cemented 

 by yet more granular quartz and some 'accessory shreds of sericite. The quartz 

 grains are usually strained, if not actually fractured. Probably more than 90 



