DALY: PIIYSIOGRArHY OF ACADIA. 95 



If the lowland were existent in pre-Cretaceous time, it must have 

 been submerged to greater or less depth during the Cretaceous cycle, 

 and sediments of that age must have been laid in the trough. While 

 most of such a filling might have been removed during the Tertiary 

 cycle, we should hardly expect that every trace of it would have 

 vanished. Nor is it conceivable that the present surface of the low- 

 lands represents down-warped or down-faulted portions of the Cretaceous 

 peneplain. Neither faults nor warps would so faithfully occur only 

 where the soft Carboniferous rocks appear ; yet in this part of Acadia 

 the Carboniferous rocks and the lowlands are coextensive. No fact 

 regarding the lithology of these sediments is more strikingly brought 

 home to the field-observer than their similarity to those of Triassic age 

 in the Fundy trough, — a similarity which goes far to explain the long 

 delay in transferring the red sandstones of Prince Edward Island from 

 the Triassic to the Carboniferous division, where recent determinations 

 would place them. The rocks of both periods are about equally con- 

 solidated and equally resistant to atmospheric wasting. If the Annapolis 

 Valley be the product of erosion in the Tertiary cycle, we must agree to 

 the possibility of similarly profound dissection of the Cretaceous peneplain 

 in the Carboniferous tracts. 



For these reasons, and on account of the agreement of summit-levels 

 on Triassic and Carboniferous rocks at the head of the Bay of Fundy, it 

 is highly probable that the lowland surface from St. Mary's Bay to 

 Northumberland Strait belongs to one great plain of denudation dating 

 from the end of the Tertiary cycle. This plain is a secondary peneplain, 

 and is believed to extend over Prince Edward Island and the Carbo- 

 niferous lowland of Central New Brunswick. Its longitudinal valleys 

 described by Sir William Dawson are regarded as the product of adjust- 

 ment. Surmounting the plain are monadnocks like Springhill (610 feet), 

 Claremout Hill (565 feet), Windham Hill (600 feet) in the Cumberland 

 district, Indian Mountain north of Moncton, and the 500-foot hills in 

 the interior of Prince Edward Island. The Cobequid Plateau is of the 

 nature of a "catoctin." The steep-walled gorges through the plateau 

 at Wentworth and at Halfway River are conceivably of the nature of 

 "shut-ins," and due to the erosive work of transverse streams let down 

 from the levels of the Cretaceous peneplain. The latter notch was low- 

 ered as fast as the soft Carboniferous rocks were removed in the lowlands 

 by a stream persistent in its course until glacial times. The rock-basin 

 of Folly Lake seems to show that the Wentworth notch early became a 

 wind-gap during the Tertiary cycle. Chalmers ('95, p. 13) suggested an 



