in 



Eastern North America. -±05 



red beds, gypsum, and dolomites, the last of which have 

 an abundance of peculiar marine organisms. The age of 

 all of these deposits is late Mississippian. Then a time 

 of marked mountain-making again set in, and this, the sec- 

 ond orogenic period, appears to have been the strongest 

 of the four Carboniferous deformations, for it removed 

 the sea permanently from the entire area of the Maritime 

 Provinces of Canada. It seemingly took place during 

 latest Mississippian time. The succeeding deposits, by 

 their overlapping and transgressive character, all show 

 more or less of an angular unconformity beneath. The 

 first of these Pennsylvanian fresh-water deposits are the 

 conglomerates of southern New Brunswick, followed by 

 the Lower Westphalian coal series of New Glasgow, the 

 Fern Ledges of St. John, and in part the Millstone Grit 

 of the Sydney area and Prince Edward Island, together 

 having a thickness of more than 5,000 feet. Next came 

 the third orogenic movement, of about middle Westpha- 

 lian time, resulting in the conglomerates of the Joggins, 

 Parrsboro, and New Glasgow areas, and the late West- 

 phalian coal series of the Joggins basin, with a total thick- 

 ness of more than 6800 feet. Now followed the last of the 

 four Carboniferous deformations, one of the latest or 

 post-Westphalian time, and this elevation gave rise to 

 the higher conglomerates of the Joggins area and the 

 Lower Stephanian coal series of Sydney, whose thickness 

 is not less than 2100 feet. In Prince Edward Island, the 

 thickness just mentioned appears to swell out to nearer 

 6000 feet. There was another deformation later, since 

 none of the Carboniferous strata remain in their original 

 attitude of deposition. 



The term orogeny has to do, as we have seen, with the 

 making of mountains, and the defined names that we 

 apply to the result of a given deformation, as the Acadian 

 Mountains, point out the place and time of their making. 

 For instance, the Acadian Mountains rose in late Devo- 

 nian time and extended from the New England States 

 through New Brunswick and Nova Scotia into Newfound- 

 land. On the other hand, we need a term to direct atten- 

 tion to mountains that we do not see, and may never see, 

 but whose presence is clearly demonstrated in the thick 

 and often coarse sedimentary deposits resulting from 

 their waste. We therefore propose to use the term oro- 

 dasy (from oros, mountain, and Mao, break in pieces), 



