280 J. B. WOOD^VORTH APPALACHIANS IX XEAV EXGLAXD 



exhibited mountain structures of the Middle or VPP^^ Devonian of the 

 Acadian region. The prevailing tendency of volcanoes to break out on 

 the coastal slope of the great Tertiary ranges of the globe finds in this 

 distribution some analogy and suggests that the Xorth Atlantic basin 

 was forming, if not in existence, beyond the present continental border, 

 despite the fact that we find no evidence of it as a great north-south 

 trench on the border of the continent until after the dawn of the Cre- 

 taceous period. 



The Tkiassic xormal Fault Blocks 



The normal faulting, which rose to its maximum displacements after 

 the Xewark formations of Upper Triassic time, has raised and lowered 

 •differentially portions of the Paleozoic strata in Massachusetts. As Bar- 

 rell pointed out, the block between the Connecticut and the Hudson rivers 

 has the appearance of having been arched up midway between its de- 

 pressed edges on the east and west. This is especially true of the cross- 

 section through the State of Connecticut to the western border of the 

 Triassic area in southeastern New York and northeastern New Jerse}'. 

 According to conservative estimates of the downthroAv of the Triassic 

 strata, where greatest, in New Jersey and Connecticut along the western 

 and eastern boundary faults respectively of this block, the relative dis- 

 placement appears to be as great as two miles vertically. Some part or 

 all of this vertical displacement may be attributed to the relative uplift 

 •of the Paleozoic and older rocks on the outer sides of the block in ques- 

 tion. What we note is that the region of flat-lying schists in central 

 Massachusetts stands relatively higher today than it did in mid-Triassic 

 time, when compared with the sedimentary base in Newark time (Upper 

 Triassic). 



The eastern limit of the wide fault block to the east of the Connecticut 

 Yalley would seem to be found in the bounding fault of the Triassic area 

 •of the Bay of Fundy and the New Brunswick shore. Erosion has jDrob- 

 -ably very largely removed the Triassic from a former extension south- 

 ward over the floor of the Bay of Maine. The southwestward continua- 

 tion of the fault along the west side of the Bay of Fundy to Cape Cod 

 Bay is a matter of conjecture, supported only by the remarkable depres- 

 sion of the bedrock surface off the eastern coast of northeastern Massa- 

 chusetts and by the ilianner in which the break in the surface is staked 

 out by the marked earthquakes of colonial times at Plymouth in 1(338, 

 Newbury in 1727, and the vicinity of Scituate in 1755 — three valid 

 •S3Tnptoms of a fault existing along or off that coast. 



