118 BULLETIN OF THE 



arrangement parallel to the adjacent surface of the sandstone. The 

 glassy base with its accompanying dots of ferrite is best shown in sections 

 from the narrow leaders running into the overlying sandstone (Fig. 12). 

 These leaders penetrate the sandstone for a distance of several feet ; 

 the largest, which is three inches wide at its beginning and over twenty 

 feet long, is seen under the microscope to be nearly pure glass, in which 

 minute double refracting areas are abundant ; the smallest leaders are 

 mere threads, and in composition are essentially glass. 



Although as a whole the western trap is little changed, marked al- 

 teration and hydration are shown in the upper surface of the trap of 

 Gaylord's Mountain, and in the leaders ; and it is to be noticed in con- 

 nection with the much greater hydration of tlie Saltonstall ranoje, that 

 this zone of glassy trap corresponds to the general glassy base of the 

 extrusive sheets. By the association of the intrusive trap at Roaring 

 Brook with the coarse sandstone immediately above, it has probably been 

 brought into contact with water to a greater or less extent, and part of 

 its alteration may be attributable to this cause. No amygdules occur 

 in tlie trap, except rarely one of a pseud-amygdaloidal character; there 

 is no tendency towards a mixtui'e of the two rocks along the line of 

 junction, either of the kind seen above the extrusions or like the brec- 

 cias known with certain intrusions. 



The microscope affords no evidence that the conglomeratic sandstone 

 has been indurated by heat. The sandstone is much decomposed, owing 

 to alteration of its feldspathic constituents, and its grains are somewhat 

 incoherent. This failure to show induration does not, however, militate 

 against tlie intrusive origin of the trap. Similar sandstone at the base 

 of Saltonstall Mountain exhibits no greater evidence of heat induration, 

 although it was surely subjected to a high temperature. 



As far as Vjoth microscopical and field evidence go, there can be no 

 doubt that in the case of Gaylord's Mountain we have a well marked 

 example of an intrusive sheet. No observers have given it a different 

 interpretation. 



The Ash-bed in the Lamentation Anterior. Locality 8 (Fig. 5). — Two 

 miles north of Meriden, near the road leading to New Britain, the fol- 

 lowing section is exposed in the ridge anterior to Lamentation Mountain. 

 The base of the bluff on the upper slope of the ridge shows a small out- 

 crop of fine-grained, brownish red sandstone ; immediately above this 

 there are twenty or move feet of tufa-like material, containing oval and 

 discoidal areas of close-grained trap that we have interpreted as volcanic 



