[ADAMS & barlow] ALKALI SYENITES OF EASTERN ONTARIO 49 



be distinguished from it in hand specimens of the rock. One curious 

 fact in connection with this rock is that, while the nepheline syenite con- 

 tains numerous large grains of calcite, which from analogy with other 

 occurrences would naturally be regarded as derived from the disintegra- 

 tion of included masses of limestone, no limestone was found within a 

 mile of the exposure. So that, while there may be inclusions of lime- 

 stone hidden by the forest which mantles much of the surrounding dis- 

 trict, the small body of nepheline syenite seems tO' occur as an isolated 

 mass within the great body of diorite which underlies the north-eastern 

 comer of Wollaston. 



y. The Nepheline and Alkali Syenites of the Township of Methuen. 



These rocks in Methuen are confined to a single occurrence which, 

 however, is large, and fonns the most striking topographical feature in 

 the township. This is what is known as the Blue Mountain, a ridge 

 which, rising abruptly from the level country about the middle of the 

 township, stretches away to the south-west nearly to the Burleigh line, 

 where it gradually sinks again to the level of the plain. It has an 

 average height of somewhat over 200 feet above the waters of tlie Kasha- 

 bog Lake which lies immediately to the south of it, but at its northern 

 end becomes considerably bolder, reaching a height of 300 feet above the 

 waters of the lake. 



The ridge is formed of nepheline syenite associated with both the 

 white and the reddish varieties of alkali syenite, while the surrounding 

 country, as shown in the accompanying map, is underlain by amphi- 

 bolites containing thin interstratified bands of crystalline limestone, 

 both of which are cut by the granite-gneiss of the Methuen batholith. 



The intrusive mass of the Blue mountain thus possesses a slender 

 pear-shaped outline, being eight miles long and one and a half wide at 

 its widest part, near the north-east end, while the narrow south-western 

 part of the mass, where it runs through the township of Burleigh, has a 

 width of only about 200 yards. 



The Nepheline Syenite. — The normal nepheline syenite of 

 this occurrence is best exposed on the north-east half of the 

 Blue Mountain. It is light grey or white in colour and 

 of medium grain, being characterized like all the syenites of 

 this occurrence by a very low content of iron-magnesia constituents. In 

 the central and highest portion of this north-eastern part, the rock is 

 massive in character, but on either side the rock develops a more or less 

 well marked foliation or parallelism of constituent minerals, which, how- 

 Sec. IV., 1907. 4. 



