73 



into which the constitutens of the pegmatite have grown 

 with well defined crystal faces. 



Geology in the Vicinity of Gooderham. 



From the road crossing about one and a half miles 

 (2-4 km.) to the east of Gooderham station, the party will 

 walk southward for two and a half miles (4 km.) 



This road in the first half mile crosses a sand plain 

 through which Burnt river meanders. Then the party 

 will cross lot 30 of Con. V. of the Township of Glamorgan 

 by a trail leading southwards, passing over crystalline 

 limestone to a large occurrence of an albite-rich variety 

 of nepheline syenite containing a hornblende allied to 

 hastingsite. This rock is distinctly foliated, of medium 

 grained texture, with schlieren of coarse grained nepheline 

 syenite pegmatite. The micaceous constituent is biotite, 

 not lepidomelane. 



This is succeeded by crystalline limestone penetrated 

 by masses of a remarkable nepheline syenite pegmatite. 

 One exposure on lot 30, Con. IV, has been opened up by 

 blasting. The rock, as shown in the accompanying 

 illustration, consists essentially of nepheline and albite. 

 with occasional individuals or small masses of coarsely- 

 crystalline calcite. The iron-magnesia constituents — 

 chiefly biotite — are present in very small amount, and over 

 large surfaces are entirely absent. A black hornblende, 

 as well as a little pyrrhotite, may also be seen. The rock 

 contains masses of pure nepheline which in places measure 

 a yard in diameter. Sodalite is also occasionally repre- 

 sented as irregular masses sometimes two inches in dia- 

 meter, included in the large masses of nepheline and having 

 apparently been derived from them by secondary action. 

 The party will then go to a point by the roadside on 

 lot 29 of Con. Ill, where a good view over the district to 

 the north can be obtained, and whence, on a clear day, 

 the character of the peneplain can be seen (see p. 11.) 



The country rock at this point shows one phase of the 

 gabbro of a great intrusion which underlies a large area of the 

 country to the south. This intrusion has a length of 

 eight miles (12-9 km.) and a maximum width of two and 

 a half miles (4. km.). The gabbro composing it shows a 

 very marked variation in composition from place to place, 

 ranging in character from a rock in which plagioclase pre— 



