cii GENERAL SUMMARY OF SCIENTIFIC AND 



turned dips are such that the Hudson River slates, accord- 

 ing to Fontaine, rest upon the Devonian, and even upon the 

 Lower Carboniferous of the North Mountain. Similar ob- 

 servations were long since, in this region, made by Rogers, 

 -.Emmons, and Lesley. In other parts of the valley, however, 

 this state of things does not exist, and the more ancient 

 slates and conglomerates repose with a high northwest dip 

 on the flank of the Blue Ridge. 



An important deduction by Fontaine, from his examina- 

 tions of the rocks in Virginia, is that there is no ground for 

 the conclusions of H. D. Rogers that the folds of the Ap- 

 palachian system extend to the Atlantic, and are more com- 

 pressed next the ocean, while widening out to the west. In 

 fact, the White Mountain rocks of the eastern are less dis- 

 turbed than the Huronian of the middle belt. " Such a 

 connection does exist between the flexures of the Silurian, 

 Devonian, and Carboniferous areas, but the Blue Ridge is 

 the initial point on the east." 



The writer may remark in this connection that these 

 strata from Harper's Ferry, for a few miles east along the 

 Baltimore and Ohio Railway, offer all the types of the Huro- 

 nian or Green Mountain series, while the gneisses and mica- 

 schists nearer Baltimore present the characters of the Mont- 

 alban or White Mountain series. Pebbles of these latter 

 rocks, derived from the Blue Ridge, abound in the con- 

 glomerates which with sandstones and shales make up the 

 Iron Mountain on the southeast side of the great Appa- 

 lachian valley in Grayson County, Virginia. 



Dawson has lately discussed anew the facts with regard 

 to some of the Eozoic rocks of Canada, recalling his old ob- 

 servation that the post-Laurentian which in Madoc, Ontario, 

 contain eozoon, present also forms like Scolithus. He has 

 as;ain studied the conditions under which Eozoon Ccmadense 

 occurs in its original locality on the Ottawa, in the prov- 

 ince of Quebec. The eozoal limestone forms a thick belt in 

 the gneiss, but the eozoon is abundant only in a bed of four 

 feet, which contains bands and concretions of serpentine, 

 and is traversed by veins of chrysotile. Along with these 

 are laminated masses of serpentine and calcite which are 

 entire specimens of eozoon. Fragmental portions retaining 

 the structure of eozoon. are also dispersed in layers through 



