84 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



would carry it over much of the Cobequids just tangent to the surface 

 and into the rest of the massif, nowhere cutt-ng it more than four hun- 

 dred feet below its highest point. This close correspondence between 

 the two plateau surfaces is explained by the assumption of one continu- 

 ous peneplain as once having covered both plateaus and the intervening 

 space. At the same time, it is possible that long low residuals of the 

 " Unaka " type l overlooked the peneplain in the region of what is now 

 the Cobequid belt. 



The New Brunswick Highlands. — The lack of good topographic 

 maps and of numerous accurately determined elevations is especially 

 felt when the attempt is made to carry the peneplain facet into New 

 Brunswick. Yet the grouping of facts summarized in the one-quarter 

 inch map of the Dominion Survey with those derived from written 

 reports seems to show that the facet is represented over considerable 

 areas of the upland. The strongly folded Cambrian, Silurian, Devonian, 

 and Lower Carboniferous beds wrap about the pre-Cambrian core which 

 runs parallel to Chignecto Channel and the Bay of Fundy shore. From 

 the eastern end of the range to a point about thirty miles northeast of 

 St. John, all these rocks stop off at a general level of from 1,000 to 

 1,200 feet. The surface is gently rolling and very comparable to that 

 of the Cobequid plateau. Still farther to the w r est it sinks to 

 the 600-foot contour, where it crosses the St. John River, only to 

 rise again to 1,200 feet and more on the northern arm of the massive 

 angle of the New Brunswick ancient crystallines running to Chaleur 

 Bay. Monadnocks like Bald Mt. dominate the peneplain. Below it 

 lie entrenched longitudinal valleys presumably of subsequent origin 

 (Bailey and Matthews, '72, p. 15). 



North Mountain, Digby Neck, and Long Island. — Lastly, the 

 upland surface of the great lava ridge that stretches with interruptions 

 from Cape Blomidon to Briar Island, a hundred and twenty miles away, 

 admirably represents the peneplain facet (Plates 4 and 5). Extending 

 the latter in imagination from the Southern Plateau to the New 

 Brunswick highland, the nearly plane surface thus produced is found to 

 be tangent to the summit of the intervening " mountain." From 

 Blomidon to Digby Gut, the average elevation of the flat-topped and 

 truncated ridge is about 550 feet, matching well with the 500-foot 

 sky-line of South Mountain. Southwest of the Gut, the ridge-plateau 

 breaks up into two subordinate ridges separated by a long valley. 

 Their crest-liues accord in elevation as they sink to 120 feet on Briar 



i Hayes, 19th Ann. Rept. U. S. Geol. Surv., 1899, Pt. II. p. 22. 



