BERNARDSTON SERIES OF UPPER DEVONIAN. 265 



is reached by examining the quartzite ledges along the strike north and 

 south from this point and comparing them with the "upper quartzite." 



The mica-schist tvest of the limestone (1'). — This rock, like that east of 

 and above the limestone (1 of the section) is a dark, even-bedded musco- 

 vite-schist, so fine-grained as to be almost indistinguishable from the even- 

 bedded varieties of the argillite below, with its glistening sui-face pitted 

 here and there by minute hollows from which small red dodecahedral 

 garnets have fallen out. It is abundantly marked by small bodies, which 

 appear much like minute altered chiastolites barely visible to the eye. It 

 occurs only at the bottom of the slope just west of the line of excavations 

 for limestone. (See " Petrographical description," No. 14, p. 291.) 



FniiU between the schist and the Ihnestone (d, fig. 15j. — The bed last 

 described apparently dips 25°-35° E. under the limestone, with the strike 

 N. 70° E. But just opposite and northwest of the largest excavation in 

 the limestone, under a small apple tree, where the schist seemed certainly 

 to go under the limestone, and where Professor Dana and I once dug 

 down and followed it for 6 inches under the limestone, I had excavations 

 made at a later time, having doubted the reality of the apparent conforma- 

 ble superposition because the bed of limestone rested on the schist with 

 abrupt transition and total want of continuity. I found the two rocks to 

 be faulted against each other, the wall of the limestone bending under for 

 a few inches and then going down vertically, and the schists, so flat in the 

 exposures below, were here crumpled up sharply and ground into shapeless 

 masses against the limestone. I followed the fault down nearly 4 feet 

 without finding the bottom of the limestone, but mingled in the crushed 

 schist I found fragments of the chloritic rock which lies in the limestone 

 and is exposed in the bluff to the north (fig. 18). At a later date I had 

 further excavation made, uncovering the northern blufi", where also the mica- 

 schist approached the limestone at its northern end, and I exposed here a 

 zigzag fault line between the schist on the west and the black magnetite- 

 pyrite-chlorite-limestoue, and below this between the schist and the white 

 limestone itself (e, fig. 15). The fault plane is nearly vertical. The relation 

 of the beds at this point are made plain by fig. 18 (p. 266). 



The limestone. — The limestone, which forms the center of interest of the 

 section, is exposed in many old pits, extending from the bluff overlooking 

 the brook to the largest opening overhung by birches, where the rock is 



