GLACIAL NOTCHES. 531 



Thus if, after examiiiiuo- the marked grooves under and north «.f tlie 

 Prospect House on Mount Holyoke, one goes a few rods east to the groove, 

 about 12 feet deep and of equal width, just behind the bowling alley (see fig. 

 30), one will find it hard to draw the line between them. And if, after exam- 

 ining the grooves and striae on the second peak west of tlie notch, one goes 

 down west into the deep groove about 40 feet across, the similarity in direc- 

 tion and shape will be fouml very striking; and such cases are (juite common. 



pseudo-gijAcial, stride on devonian argillites. 



While examining the garuetiferous mica-schists at Purple's quarry, in 

 the east part of Bernardston, I was attracted by a peculiar sti-iatiou which 

 occurred upon a broad, flat cleavage surface of the nearly horizontal slates 

 and continued beneath the sixperincumbent beds. The surface in question 

 was just at the north edge of the water which fills the abandoned quarry, 

 and was certainly in place and undisturbed, and I raised the slates which 

 rested upon it and followed the striation beneath for a foot or more inward 

 without seeing anything which suggested to me that these upper layers 

 were not also in place and undistm-bed. 



Clear impressed lines, from those so fine as to be .seen only with a 

 lens up to those a millimeter in diameter, covered the broad, flat surface — 

 in average about an inch apart — the larger showing a delicate longitudinal 

 striation. These grooves vary in length between quite wide limits — 1 to 6 

 inches. The larger number are straight, or neai'ly so ; very many form 

 easy open cur\'^es, single or double. Over most of the sui-face two distinct 

 systems, making an angle of 40° with each other, were apparent, the one 

 having the longer and finer lines and most of the long curving lines, the 

 other being somewhat broader, shorter, and more rigidly parallel and 

 sti-aight. Their length varied very little from an inch, and they were often 

 slightly gouged out at the end. On putting sevex'al parts together, so as to 

 get a broad surface, the finer lines of the first system are seen to bend and 

 continue in the second system. 



The whole impression was quite like that of the rain-marks on a car 

 window before and after starting. Faint traces of a third system at right 

 angles to the first are also present. The direction in the rock was not taken, 

 as the marks were supposed to be of mineral or organic origin; many of 

 them strikingly resemble in size, curvature, etc., impressions of Graptolithus 



