265 

 Miles and bcds dip beneath the Coal Measures of the 



K-ilometres. ^ 



North Sydney area. 



12-9 m. North Sydney Junction — Alt. 159 ft. 



20-8 km. (48-5 m.)- North Sydney Junction is situated 

 approximately on the axis of the synclinal fold 

 traversing the Millstone Grit area. From 

 this point, the waters of St Andrew channel 

 are visible to the northwest, with the low 

 wooded heights of Boularderie island beyond, 

 while above these are visible the highlands on 

 the western side of Great Bras d'Or. These 

 highlands, distant about 9 miles (14-5 km.) 

 rise to altitudes of 900 feet (275 m.) and form 

 the western boundary of the Sydney Carboni- 

 ferous basin. Boularderie island is mainly 

 occupied by Millstone Grit strata arranged 

 in a shallow syncline with strata of the Lime- 

 stone series occurring at intervals along the 

 southeastern and northwestern shores. The 

 anticlinal axis separating the Boularderie Island 

 syncline from the North Sydney syncline is, 

 in a general way, the prolongation of the axis 

 of the Boisdale hills. 



Leaving North Sydney Junction, the railway 

 descends towards the valley of George river. 

 The Boisdale ridge rises on the further side 

 of the river valley and after passing a small 

 lake, a quarry working in Pre-Cambrian crys- 

 talline limestone is visible on the side of the ridge. 

 The western side of the valley of George river is 

 floored with strata of the Carboniferous Lime- 

 stone series dipping to the east. The total thick- 

 ness of this series as developed in this neighbor- 

 hood is small as compared with the develop- 

 ment on the shores of Sydney harbour. Pos- 

 sibly the decreased thickness is due either to 

 faulting or to an overlap of the Millstone Grit. 



The railway crosses George river near its 

 mouth and enters the narrow area occupied 

 by the Limestone series. The railway passes 

 close to the shore around the northern end of 



