B. K. Emerson — " Bernardston Series" etc. 265 



sands on the north line of Greenfield, appearing again only in 

 the limited outcrop just west of the village of Whately, fifteen 

 miles farther south, and in one newly discovered at the month 

 of Mill River. Everywhere the slope of the West Mountain 

 shows only the black argillite, except in a single band back of 

 the house of Mr. Williams, a mile north of the village, where, 

 apparently resting upon the argillite, occurs the fossiliferous 

 series. The section has a width going up the hillside on the 

 line of dip, of only 1050 m , and is nowhere exposed, on the 

 strike, more than a tenth of this distance. The outcrops of the 

 argillite to the north and south show that there can be only a 

 very limited amount of the newer series preserved upon the 

 hillside, while the heavy accumulation of till generally prevents 

 one's seeing its limits or its contact . upon the lock below. 

 It approaches the argillite quite closely upon the west and in 

 the line of strike can not be more than 3000 m long. Over 

 against the West Mountain on the east, across the narrow valley 

 of Fall River, rises a range of hills bounded on the south and 

 east by the terrace sands, which is composed of a similar series 

 of rocks in similar succession. The principal difference between 

 the two is that on the east a dark hornblende rock, often massive, 

 takes its place in the series while the limestone and magnetite 

 bed of the typical section are wanting, and all the other mem- 

 bers are somewhat more metamorphosed. Staurolite occurs in 

 the schists, feldspar crystals and biotite in the quartzites, and 

 they are thrown into complex folds and greatly faulted. They 

 lie in fact along the center of the great synclinal of the Con- 

 necticut valley which is an area of maximum disturbance of the 

 rocks quite across the State. These discrepancies become less 

 important when it is noted that hornblende exists in consider- 

 able quantity directly above the Williams farm limestone, and 

 the second bed of the same limestone in South Vernon is encased 

 in hornblende schist. Across the river in Northfield the white 



Bernardston of central, being known to afford fossils, the former of Lower 

 Silurian age and the latter of Lower or Upper Helderberg, these were selected 

 as regions for ascertaining what kinds of crystalline rocks might be of these 

 different periods for comparison with Archaean crystalline rocks. (The Lower 

 Silurian age of the Taconic system was hardly questioned in 1873 by any one.) 

 Prof. Dana's papers on the Bernardston region describe among these rocks, 

 besides the limestone and quartzyte, garnetiferous mica schist, staurolite slate, 

 gneiss, and various hornblendic rocks, including quartz-syenite. 



Prof. Emerson has given the region a thorough investigation, in which he has 

 removed the doubts as to the relations of the beds, made out, as far as possible, 

 the system of faults and flexures, studied the rocks as to their kinds and transi- 

 tions, and determined the age of the series to be Upper Devonian. The paper 

 will be accepted in America, and should be elsewhere, as putting the facts beyond 

 doubt that gneiss, dioryte, granite, and the other crystalline rocks described are 

 not always of Archaean or pre-Cambrian make ; that dioryte and granite are not 

 always of igneous origin ; and these conclusions are made sure on the well-estab- 

 lished criterion of age, that is, fossils — Crinoids, Corals, Brachiopods. j. d. d. 



