133 



The magnetite carries traces of cobalt and 

 nickel. 



Scattered about this locality are many 

 boulders of anorthosite which carry corun- 

 dum. These rocks are found "in situ" a 

 short distance north and north-east [7, p. 

 227]. Of these boulders Dr. Miller says 

 "They are rather dark colored on the 

 weathered surface, but have a characteristic 

 bluish or purplish color, which can be made 

 out even at some distance from them, and 

 this serves to distinguish them from the 

 boulders of trap and other dark colored 

 rocks, which are associated with them. The 

 majority of the crystals of corundum have a 

 diameter of about half an inch (1-27 cm.) 

 and show a striking uniformity in size. The 

 color is light grey to almost white, and they 

 average about 5 per cent of the rock. Owing 

 to their greater hardness and durability, they 

 stand out well above the surface of the rock 

 which holds them." 



Under the microscope the anorthosite is 

 seen to consist of the basic plagioclase, by- 

 townite, with common green hornblende. 

 Scattered through the bytownite are innumer- 

 able crystallites, which are possibly corundum 

 although nothing was determined to confirm 

 this suspicion." 



PALEOZOIC-PRE-CAMBRIAN UNCONFORMITY. 



INTRODUCTION. 



Splendid opportunities for seeing the relationship of 

 the Paleozoic sedimentary rock to the old Pre-Cambrian 

 floor are to be had in the city of Kingston. On this 

 excursion several points will be visited where the Paleo- 

 zoic can be seen lying unconformably upon the Pre- 

 Cambrian. In the lower basal beds, boulders of the Pre- 

 Cambrian are cemented by a limestone mud, which 

 gradually passes upward into clean limestone beds away 

 from the actual contact. At one exposure of the Potsdam 



