Page:The Journal of geology (IA journalofgeology11893univ).pdf/288
traversed by a rude cleavage, which has a general northwesterly direction, and so makes a large angle with the line of contact. The direction of cleavage varies between the limits of N. 40° W. and N. 60° W., and is usually represented by a multitude of planes, in which the micas only are foliated. This cleavage is more strongly developed on the western side of the exposure, near the contact, than elsewhere; and as the cleavage becomes more perfect, the large orthoclase crystals disappear.
IV. Conglomerate.
The matrix of the conglomerate varies between a somewhat micaceous quartzite and a fine grained mica-schist, and shows very distinct bands differing in color, texture, and composition. These bands are thrown into little folds, about northwesterly plunging axes; in strike they conform to the direction of the line of division between the conglomerate and the granite. In this quartzitic matrix are imbedded clearly water-rounded pebbles of quartz, granite, and of a black crystalline schist. The quartz pebbles are as a rule small, few exceeding six inches in diameter. They are of different varieties, clear, milky, brown, and blue gray quartz all being represented. All are more or less thoroughly granulated. They are of very different shapes, and within the planes of bedding, their longer axes lie in different directions. All agree in being smoothly worn and are unmistakably water-rounded.
The granite fragments vary in size from pebbles a fraction of an inch up to bowlders five feet in diameter. The larger are usually thin slabs lying with their flat sides parallel to the bedding. The foliation of the matrix often follows round the inclusions. The contacts between the pebbles and matrix are exceedingly sharp; sometimes, however, where several pebbles lie close together, it is a matter of some difficulty to trace the boundary of each on the weathered surface. The distribution of pebbles is very irregular. Near the south end of the exposure they are closely packed, while the northern part of the main exposure has comparatively few. The granite of the pebbles and bowl-