4i 



uneven character of the pre-Trenton surface. At the 

 eastern end of the bridge, a path leads to the exposure on 

 the bank of the river immediately below the concrete dam 

 and just above the crest of the falls. Here the erosion of 

 the rocks have revealed the bottom of the Trenton sea, and 

 one may observe the Solenoporas growing on the sea floor, 

 the calcareous mud filling hollows and cracks in the gneiss, 

 and occasional boulders of the gneiss imbedded in the 

 lower layers of the limestone. It will also be noted that 

 the dip of the strata conforms to the irregularities in the 

 sea floor, and that, while the unconformity here represents 

 all of Cambrian and early Ordovician time, the basal 

 conglomerate is insignificant in amount, indicating that 

 this point was some distance off shore. 



These beds are the oldest at this particular point; at 

 the foot of a dam about one-half mile up the stream some- 

 what older beds outcrop which contain the oldest Trenton 

 faunules, namely those with Trocholites canadensis and 

 Parastrophia hemiplicata. All of the beds are newer than 

 the Black River. On the weathered surfaces just above 

 this exposure fossils are quite common, Trinucleus con- 

 centricus and Eheirocrinus logani (plates only) being most 

 abundant. 



From the crest of the falls on the eastern side of the river 

 it is possible to continue down along the top of this bank, 

 and near the point of the bluff facing the St. Lawrence, 

 fossiliferous gravels of the Champlain period will be found 

 with My a truncata, Saxicava, Macoma, barnacles, and 

 other fossils. Then, descending the dip slope to near the 

 railroad tracks, one may find specimens of Triarthrus 

 becki and graptolites in the Lorraine shales. 



MONTMORENCY FALLS: (c) BASE OF FALLS 



While descending on the elevator to the basin below the 

 falls the Lorraine shales on both sides of the river may be 

 seen. Proceeding up stream toward the falls, Lorraine- 

 Utica shales are seen in the bed of the stream. Near the 

 base of the falls, the fault-contact between the Utica and 

 the gneiss is crossed. From this point there is an excellent 

 view of the Pre-Cambrian gneiss along the fault plane, 

 and in the direction of Kent House, the horizontal beds of 

 the Trenton may be seen resting on the gneiss. A short 

 distance up the bank on this side a crushed zone within 



