REPORT OF THE CHIEF ASTRONOMER 59 



SESSIONAL PAPER No. 25a 



A second analysis gave the proportions of the oxides entering into solution 

 in hydrochloric acid and also the percentage of insoluble matter, as follows : — 



Insoluble in hydrochloric acid.. . . 16-02% 



Soluble in hydrochloric acid : 



Fe„0 3 1-70 



AL"0 8 -37 



CaO 2516 



MgO 16-83 



In the soluble portion CaO: MgO = 25-16: 16-83 = 1-495: 1, a ratio only 

 very slightly higher than the ratio • for true dolomite, namely, 1-4:1. The 

 carbon dioxide required to satisfy those bases is 38-28 per cent, which is close 

 to the percentage actually found. 



Considering that the alkalies belong to the feldspars and the iron oxides 

 to magnetite, the proportions of the various constituents have been calcu- 

 lated to be: — 



Calcinm carbonate 44-9 



Magnesium carbonate.. .. 35-3 



Quartz 8-0 



Orthoclase molecule 5-6 



Aibite molecule 2-6 



Magnetite 1-4 



Eemainder 2-2 



100-0 



As in the case of the Waterton dolomite it is difficult to understand the 

 bigh proportion of combined water. It may occur with the silica alone or it 

 may occur in a hydrous silicate of magnesium. About 80 per cent of the 

 rock is composed of carbonates in the form of true dolomite. 



Middle Division.- — A specimen characteristic of the middle member (zone 

 e), though not of its most sandy part, was collected at the low cliffs four 

 hundred yards east of the derrick at Oil City. 



This rock on the fresh fracture has the typical pale gray colour of the forma- 

 tion and weathers whitish to pale buff. On the weathered surface the glassy wind- 

 worn or water-worn, rounded to subangular quartz and feldspar grains stand 

 out like white currants in a flour paste. The grains are of varying size up to 

 0-3 mm. in diameter, averaging about 0-2 mm. The quartz grains are the 

 more abundant. The feldspar is chiefly a fresh and characteristic microper- 

 thite, with orthoclase in more subordinate amount. No soda-lime feldspar could 

 be demonstrated. In this analyzed specimen as in the majority of the thin 

 sections from all three members of the formation, round grains of chalcedonic 

 or cherty silica, with diameters also averaging 0-2 mm., occur in considerable 

 number. These small bodies are probably of clastic origin. Oolite grains with 

 poorly developed concentric and radial structure are likewise rather abundant 

 in both the analyzed specimens and others. Dr. H. M. Ami has noted that 

 some of these grains have a certain resemblance to radiolaria, but regards their 

 inorganic, concretionary origin as more probable. 



