298 RECORDS OF POST-TRIASSIC CHANGES 



heading back to a low divide some three or four miles from the 

 coast. 



During the submergence of the region in late M^sozoic or 

 early Tertiary times, the streams were drowned by the sea and 

 the silicious and calcareous deposits described were laid down in 

 the old river valleys Deposits forming in this way would be 

 protected from the disturbances of the open shore, and probably 

 be composed of fine sediment laid bare at each low tide and dried 

 and sun cracked in bright warm days until carried below the 

 tidal limits by the slow subsidence of the whole region. The 

 limestone deposits indicate a submergence great enough to have 

 forme 1 large inland basins in the broad valleys in the sandstone 

 country .south-east of the edge of the trap sheet. These were pos- 

 sibly separated from each other by low divides which would be 

 gradually lessened by the rapid vertical decay of this rock refer- 

 red to earlier in this paper. When once covered by the sea, the 

 swiftly moving north-east and south west tidal currents char- 

 acteristic of this region would scour out the valley at a rapid 

 ivte, while the trap sheet would not retreat along its edges at a 

 corresponding rate since the frost work had not yet been 

 inaugurated, mild and warm climates extending at this time 

 even within the Arctic Circle. On the re-elevation of the country 

 in middle or late Tertiary times, the rivers would not return to 

 their ancient channels across the trap which were now higher 

 than the valley floor and filled in with deposits of the kind 

 described, but would flow along the valley parallel with the 

 mountain in either direction only discharging at the lowest out- 

 lets as Digby Gut at the south-west and Minas Basin and Channel 

 at the north-east. 



The colder climates of late Tertiary times were now setting 

 in with winter frosts and snow, and the sheet of trap would 

 b-gin the rapid horizontal retreat which has continued until the 

 present day. 



Boulder Clay. 



Boulder clay containing many striated stones from local 

 sources occurs throughout this whole region and is seldom absent 



