OF PEBBLES IN CONGLOMERATES. 483 



good examples of pebbles wbicli have been distorted and altered ; and it would certainly 

 be bard to find more satisfactory evidence of this sort of geological metamorphism. Upon 

 the ground the evidence of severe compression, at right angles to the plane of the dip and 

 strike of the beds, is entirely conclusive. Exposures of hundreds of square feet may be 

 seen where every pebble, granite, sandstone, schist, and quartz, has been flattened, and the 

 whole mass of pebbles and cement so jammed and crowded together, as to settle the question 

 as to the direction and nature of the force which has been at work. 



The conglomerate at Eangely Lake consists of a series of nearly vertical beds, having a 

 direction, or strike, of N. 65° E., S. 65° W., (magnetic var. 15° W., in 1867), and a breadth, 

 measuring across the upturned edges, at right angles to the strike, of about a mile and a 

 half. How far the formation extends in the direction of the strike, N. E. and S. W., has not 

 been ascertained ; it crosses the eastern end of Rangely Lake, and is well seen at the mouth 

 of the stream flowing into the head of the lake from Long Pond. The conglomerate is 

 bounded upon the north-west by schists, having the same strike, and a vertical dip ; which 

 latter, however, decreases in going N. W., dipping about 70° E. at five or six miles from the 

 conglomerate. Upon the south-east the conglomerate passes into, or is bounded by, a schist 

 having the same strike, but dipping about 45° S. E. This change in the dip, from vertical 

 to 45°, seems to occur suddenly, at or near the small stream called Saddleback Brook, and 

 most likely indicates a fault at that place. The conglomerate is not known to appear 

 either east or west of the adjoining schists ; and we should hardly expect that it would, for 

 we cannot suppose that the whole width of the conglomerate, one and a half miles measured 

 across the upturned edges of the vertical beds, represents only the simple thickness of the 

 formation. It is more likely that the conglomerate alone embraces a number of closely 

 compressed folds, of which the summits have been denuded. These upturned ledges present 

 successive beds of slate, of schist, free from pebbles, and beds almost wholly made up of 

 pebbles ; such beds being from a few inches to several feet in thickness, and joining each 

 other in some cases in a sudden manner, and in other instances in a transitional way. In 

 some of the beds the pebbles are nearly all large, i. c, from three to six inches in diameter ; 

 in others they are smaller, from a fourth to a half of an inch in diameter, and in others 

 as fine as gravel. The pebbles may be seen in all conditions, from being very distinct and em- 

 bedded in a separate matrix, to being so undefined as with difficulty to be made out. In some 

 cases, a fresh fracture shows pebbles so like the matrix, both in color and in mineral charac- 

 ter, as to be indistinguishable at a distance of half a dozen feet ; the whole mass appearing 

 like a granite, or a syenite, while it is certainly an altered conglomerate. It is to be observed, 

 however, that upon the ground no such thing occurs as a regular progression from conglom- 

 erate to granite ; but the beds in various degrees of alteration occur, one after the other, in 

 no apparent order. 



The Messrs. Hitchcock maintain: First, That the pebbles have been flattened and dis- 

 torted by compression, acting at right angles to the plane of the dip and strike ; and of this 

 we think there can be no doubt whatever. The distorted pebbles occur where the beds 

 have been folded into waves and jammed closely together. Such a folding as this could 

 result only from an intense horizontal force, and such a force would be precisely that needed 

 for flattening and indenting the pebbles as we see them upon the ground. The parallel 

 vertical position of the beds, and the flattened pebbles, with their planes parallel with the 

 bedding, we regard as the results of a common operation ; and that operation an intense 



