386 



may have reached the sea by a number of channels, but 

 eventually they appear to have broken over and then 

 through the comparatively low rocky ridge at Suspension 

 bridge and to have found their way to the sea by means of 

 the old valley entered at this place. 



The rocks forming the walls of the canyon-like outlet 

 of the St. John river at Suspension bridge are of Pre-Cam- 

 brian, Cambrian and Ordovician age. The strata of 

 these three groups are separated from one another by 

 faults that strike in a northeasterly direction. The strata 

 are, in general, steeply inclined and strike in an easterly 

 direction. 



The Pre-Cambrian measures outcrop on both sides of 

 the constricted passageway of the St. John and form the 

 northern portion of the walls. They are bounded on the 

 south by Cambrian beds from which they are separated by 

 a fault. The Pre-Cambrian at this place is represented by 

 a band of quartzite flanked on the south by a band of 

 crystalline limestone with beds of black slates and sills 

 or dykes of diabase. The strata are folded, faulted and 

 torn, but in general stand with nearly vertical attitudes. 



The Cambrian rocks are largely dark slates and fine 

 sandstone. On the eastern banks of the gorge they form 

 a narrow band separated by a fault from the Pre-Cambrian 

 on the north and by another fault from the Ordovician on 

 the south. These beds have been assigned to the Johannian 

 by Dr. Matthew. The measures bounded by the same 

 faults, occur on the western side of the narrows of the river. 

 They are bounded on the north by Pre-Cambrian rocks 

 while on the south side lie conglomerate, sandstone and 

 shale beds probably of another horizon of the Cambrian, 

 not the Johannian. 



The Ordovician measures are largely dark shales. They 

 are exposed in a narrow band along the northern shore of 

 the river below Suspension bridge. The shales are not 

 very fossiliferous, and contain only a few species which 

 are common. Tetragra-ptiis qiiadrihranchiatus is the most 

 common fossil, others being species of Didymograptus, 

 Clonograptus and Loganograptus, beside the brachiopods, 

 Orthis electra major, and Strophomena atava. The 

 Ordovician beds are overturned since they dip southward 

 at high angles thus appearing to underlie the Cambrian 

 strata outcropping on the opposite, southern bank of the 

 tidal river. The Ordovician measures are the highest 



