THE MONSON GNEISS. 63 



As far as we may judge from the chemical and mineralogical composition, tliese 

 Monson granites should remain practically unchanged for an indefinite length of time, 

 since those constituents which favor disintegration are present in unusually small 

 proportion. 



Yours, truly, John M. Ordwat, 



Professor Industrial Chemistry. 



STRENGTH OF THE MONSON GNEISS. 



Interesting data concerning the strength and durabihty of tlie Monson 

 granite are given by Mr. A. P. Men-ill. A block 7.6 by 7.4 inches, placed 

 with the bedding horizontal, was ci'ushed by a weight of 1.5,390 pounds to 

 the square inch, and one 6 by 6.1 inches, with the bedding vertical, wa,s 

 crashed by a weight of 12,720 pounds to the square inch.' These results 

 may be compared with those given for the Becket rock on page 3C. 



CONGLOMERATE STRUCTIRE IN THE MONSON GNEISS, AND SUDDEN E.\PANSIOX OF THE KO<:K I.V 



QUARRYING. 



The tri mm ings of Williston Hall, one of the buildings of Amherst 

 College, was made of rock from the Monson quarries. I had been familiar 

 with the buildings since my college days, and I was startled, two years ago, 

 upon obsei-ving distinct traces of pebbles in the blocks forming the coign on 

 the northeast corner, esjiecially in those between 8 and 12 feet from the 

 ground. PI. I, coign of Williston Hall, Amherst College, represents these 

 blocks, and is copied from a photogi'aph. A little later I discovered traces of 

 the same structure in the quarry at Monson, in a portion of the rock 6 or 8 

 feet square, near the surface of the ledge, and a rod north of the ti-ap dike 

 that intersects the quarry. I took a photograph of the wall, and the next 

 year found the whole quarried away and secui-ed a photograph of one large 

 block which had recently been blasted from the spot. These pebbles were 

 uniformly compressed, so that they were of a flattened egg-shape; the 

 shortest diameter, about an inch or an inch and a half, was east and west; 

 the next, 2 inches, was north and south, and the longest, nearly 3 to 4 

 inches, was vertical. The foliation here stands nearly vertical and strikes 

 north and south; the gneiss lies in the core of a close-pressed anticline, 

 and the pebbles have been flattened in the foliation plane by an east-west 



' stones for Building and Decoration, Xew York, 1891, p. 406. 



