387 



preserved members of an overturned syncline which in- 

 cludes the Dictyonema beds of Navy island situated about 

 I mile (i-6 km.) to the northeast on the southern side of 

 the channel. The thin-bedded, dark shales on Navy 

 island, are, in places, extremely fossiliferous, Dictyonema 

 flabelliforme being particularly abundant. Separated 

 cranidia of trilobites are not uncommon, associated with 

 the Dictyonemas, some of the species found here being 

 Parabolina heres grandis, Parabolinella posthuma, Lepto- 

 plastus latus, and Ctenopyge flagillifer. 



DETAILED DESCRIPTION. 



At the end of the street car line on Douglas avenue, 

 at the railway crossing, are exposures of Pre-Cambrian, 

 white, crystalline limestone. The railway runs along 

 the course of the fault separating the Pre-Cambrian 

 from the Cambrian. In the rock cuttings along the north 

 side of the railway, the Pre-Cambrian limestone is ex- 

 posed, while on the south side of the railway steeply 

 inclined, bent and twisted, dark slates and fine grained 

 sandstones of Cambrian, (Johannian) age outcrop. 



The position of the fault bounding the Cambrian on the 

 south is indicated by certain exposures on the Strait Shore 

 road which joins Douglas avenue about 200 feet (60 m.) 

 beyond the railway crossing. On the Strait Shore road 

 about 50 yards (45 m.) east of the junction with Douglas 

 avenue, are outcrops of twisted and torn, Cambrian slates 

 and sandstones. These measures are exposed on the north 

 side of the road, while in the gutter on the same side of the 

 road are exposures of dark shales supposedly of Ordovician 

 age since they are lithologically very similar to the grap- 

 tolite-bearing beds of this age outcropping a few yards to the 

 south in the cliffs along the shore of the river. The fault 

 plane separating the Cambrian and Ordovician, is visible 

 in the cliff face at a point just opposite the anchor pier of 

 the Suspension bridge. 



From a view point on the western shore between the two 

 bridges, the fault separating the Pre-Cambrian and 

 Cambrian is plainly indicated in the steep rock cliffs about 

 20 feet (6 m.) south of the railway bridge. The position of 

 the nearly vertical fault is made apparent by the contrast 

 between the white, Pre-Cambrian limestone on the north 

 35063— I2|a 



