456 B. K. EMEKSON — OX THE TRIASSIC OF MASSACHUSETTS. 



theu continues toward the north end of the basin, skirting an area on the 

 west wholly free from feldspathic rocks. On the eastern side the Northfield 

 schists appear in the conglomerate in Northfield and down past Miller's 

 Falls ; that is, southward beyond their place of occurrence in the shoreward 

 hills. 



Then the porphyritic granite projects through the conglomerate, as rep- 

 resented on the map at the center of the small circle drawn just south of the 

 southernmost point of the railway between Miller's Falls and Greenfield. 

 Its contributions are trailed off southward a long way, as are those of the 

 Whitmore's Ferry schists represented by the center of the circle next south 

 on the river. The area of schist around Amherst is crowded with granite 

 veins, and the schist and quartzite conglomerate is carried southward over 

 this for about four miles before the feldspathic material becomes predomi- 

 nant, and an arkose results which is then carried southward, blending for a 

 distance with the arkose from the western side. 



All the boundaries between the three classes of sediments here discussed 

 are boundaries between practically contemporaneous deposits, and so are 

 bands rather than lines ; and, with the thick coating of Pleistocene beds, 

 they can be traced only approximately. 



The contemporaneous trap sheets and the tufa beds rest on all the three 

 kinds of rock at once, showing that they are facies of a single formation. 



A similar line might have been drawn, starting at Holyoke and running 

 parallel with the trap ridge on the west, and through Chicopee Falls and 

 Springfield on the east to the southern line of the state, about four miles 

 east of the Connecticut river, which should include the black-and-red shales 

 with concretionary limestones. 



Although foreign to the subject of this paper, I may call attention to the 

 interesting series of volcanic plugs which run parallel to and about a mile 

 south of the greatly faulted Holyoke trap bed. 



