INDUSTRIAL PROGRESS DURING THE YEAR 1875. c i 



force as we proceed southwestward. Resting unconformably 

 on both sides of this ancient series is a group of schist- 

 ose rocks which to the northward conceal the Laurentian. 

 This series, which consists in large part of argillites and mi- 

 caceous and chloritic schists, with epidotic, hornblendic, 

 feldspathic, and quartzose admixtures, he compares to the 

 Green Mountain series, and suggests that they may be Hu- 

 ronian. To the east of the Laurentian, and apparently oc- 

 cupying a synclinal, in the schists just mentioned, is a series 

 of folded limestones, with micaceous schists, quartzites, and 

 roofing-slates, closely resembling the Taconic rocks of Berk- 

 shire County, Massachusetts, and apparently the prolonga- 

 tion of the Taconic belt indicated by Emmons to the east 

 of the Blue Ridge in North Carolina, and described by him 

 as extending northward through Virginia, into Maryland. 

 This, Fontaine thinks, may be altered Silurian, but he speaks 

 with doubt. These crystalline schists to the east of the 

 Laurentian axis are designated as the middle belt, and be- 

 yond is still an eastern belt of well-defined granitoid gneisses, 

 overlaid by mica-schists with gneisses, often hornblendic, dis- 

 posed in broad anticlinals and synclinals, with dips of from 

 40 to 50 to the east and west. These are said to have the 

 characters of the White Mountain series. 



Along the western flank of the Blue Ridge, resting uncon- 

 formably upon the crystalline strata, is a series of sandstones, 

 shales, and conglomerates, rapidly augmenting in thickness 

 to the southwest, and attaining in the middle of the state 

 over 2000 feet, though not over 1000 feet at Harper's 

 Ferry. These strata, which underlie the so-called Calcifer- 

 ous formation, are destitute of all traces of organic remains 

 except Scolithus. They contain in the conglomerates peb- 

 bles of the crystalline argillites (Huronian), as well as feld- 

 spar and kaolin from the old Laurentian gneisses, showing, 

 as Fontaine remarks, that these crystalline rocks formed the 

 border of the ancient sea. The strata to the northwest 

 have been greatly folded and faulted, so that these beds in 

 many parts plunge beneath the crystalline Huronian schists, 

 the two dipping at high angles to the southeast, though un- 

 conformable. The limestones, which, near Harper's Ferry, 

 include a bed of limonite, also dip southeast at a very high 

 angle. In some parts of the valley the foldings and over- 



