142 PROBABLE CHANGES IN DRAINAGE 



In viewing this region I have considered it as the inner margin 

 of an elevated ancient coastal plain, the outer or seaward margin 

 being near the Bay of Fundy where the underlying rocks dip 

 north-westerly towards the shore. If my supposition be well 

 founded the earliest lines of drainage to be established on this 

 surface, would follow the surface of the ground and run as a 

 consequent stream, taking the shortest course to the sea, across 

 the strike of the strata parallel to the dip. This is the law of 

 coastal plain drainage, and I think there is reason to believe that 

 the Black River took this course through the Deep Hollow. 



I have located a large meandering gorge in the North Mountain 

 nearly opposite the Deep Hollow, and this may be its old outlet 

 into the Bay of* Fundy. Be this as it may, the fact is well es- 

 tablished that when anticlines and synclines are eroded their 

 remaining portions form a series of ridges like the cuestas of a 

 coastal plain, and that the earliest drainage over those eroded 

 structures is parallel to the dip, and the later rivers and tribu- 

 taries develop by running at right angles to these, that is, parallel 

 to the strike. 



Judging from the structure and position, I have assumed that 

 the Deep Hollow was once the northerly extension of the Black 

 River. This river shows many signs of great age. By this 

 expression I mean stage of development. Its meanderings are 

 well incised into the hard slates and quartzites, its only signs 

 of youth being its falls which are situated near its junction with 

 the Gaspereau. I think however these falls do not necessarily 

 show youth, but are the result of the uplift in this region which 

 brought near the surface the dyke of hard diorite that crosses 

 this stream. But the river has cut deeply into this dyke, thus 

 showing this uplift to Ije greatly remote in time. 



The Gaspereau River on the other hand has no incised mean- 

 derings and its appearance is far more youthful. 



The probable history of these rivers may be stated as follows: 

 When the Black River began its flow the whole region was well 

 elevated above sea level, and as time elapsed it cut its valley 

 and its drainage area to a very low grade. In this stage of devel- 

 opment it meandered lazily over its flood plain, thus outlining 

 the present Deep Hollow. Then a period of uplift began, 

 giving the river a high grade and enabling it to cut its course 

 into the bed rock below. Probably the Gaspereau was just be- 



