•/. />. Dana — Archaean a item V. America, ">» , . > 



Why there should be bo large an Archaean-ribbed projection 

 of the continent north of the parallel of L2 . and Little corn 

 ponding to it farther Bonth awaits explanation. It may be 

 connected with the fact that the continental margin north of 

 12 is backed bo closely by the eastern arm of the V'-shaped 



Arclnvan nucleus, which is here made up of the Adirondack.^ 

 and the hills just north of the St. Lawrence. And the land- 



rd bend of the protaxis and AUeganies south of lat. 42 \. 



ito a west-BOnthwest COnrse) across central Pennsylvania (and 



paralleled in the coast line) may have the reverse cause.* The 

 trough between the A.dirondacks~and*Canada Archaean and the 



protaxis — the St. Lawivnce-( diamplain trough — is not fifty miles 

 in mean width. This trough was an open channel to the In- 

 terior Continental Bea receiving thick rock deposits until the 

 close of the Lower Silurian ; but at this epoch the Lake Cham- 

 plain portion ceased rock-making extemporaneously with the 

 formation of the Taconic Mountains and the general uplift of 

 the Green Mountain area along the western New England bor- 

 der, not to resume it again except temporarily. 



77" Ranges, — The ranges, partly or wholly Archaean, lying 

 to the east of the Protaxial Range are the following — num- 

 bering the protaxis 1, as it is the first in the series: 



II The New Hampshire Range : extending from the bor- 

 ders of Maine and Canada through Xew Hampshire and Mas- 

 sachusetts into Connecticut, making the east side of the Con- 

 necticut Valley. 



III. The Mount Desert Range : commencing near Chaleur 

 Bay, on the Gulf of St. Lawrence, and continued southwest- 

 ward through Xew Brunswick to the coast of Maine, where it 

 includes the Mt. Desert region, and thence into eastern Massa- 

 chusetts between Boston and Worcester, and probably into Con- 

 necticut. 



IV. The ACADIAN Range: commencing in the western 

 part of northern Newfoundland, east of White Bay and ex- 

 tending thence to St. George Bay and Cape May in south- 

 western, and beyond over eastern Nova Scotia; and thence, 

 probably, beneath the sea along the course of shallow sound- 

 ing-, ae sustained by Professor W. O. Crosby, to Plymouth and 

 ("ape Cod in eastern Massachusetts. 



The Archaean ridge of the long northwestern arm of New- 

 foundland, north of the Bay of Islands, making the northern 

 part 01 the SO-called " Long Range," is a more western range 

 than the preceding: it is separated from the Archaean region 

 of Labrador by the Delleile strait or channel. 



* The landward bend of the Rook} Mountain protaxis (Archaean) in Montana 



and Idaho ito the east-southeae en the parallels of 42° and \~> may h.v 



like origin — the bend lih the Atlantic ride { being opposite the southern 



extremity of the nucleal V. 



