192 GEOLOGY OF THE I^AKEAGANSETT BASIK 



BBIDG^BWATEU ABEA. 



The available exposures from Brockton southward through the Bridge- 

 waters indicate a broad syncline with low dips, and hence a much more 

 shallow trough than that near Mansfield. Southerly dips are found in out 

 crops from the granitites north of Brockton for a mile or more to the fe0u.th 

 of that city. At Cochesett, and thence southward, northerly dips are 

 encountered as far as the northern part of the Taunton and Middleboro 

 quadrangles, in the vicinity of Scotland, about 3 miles south of the limits of 

 the Dedham quadrangle. 



Overlying the chocolate-colored sandstones at Brockton, described 

 under the head of the Wamsutta group, occur arenaceous and argillaceous 

 strata of slaty structure. Exposures of a bluish coarse sandstone have 

 been made in opening new highways noi'thwest of Campello, at the corner 

 of Adams and Center streets. One and a half miles south-southeast from 

 this locality, on the west side of Salisbury Plain River, bluish-green slates 

 form a small outcrop. The cleavage is E.-W,, and dips 45^ N., the*pre- 

 vailing direction and steep dip along the northei*n border. Bowlders of 

 grayish sandstone occur in the vicinity. 



Going southward across the strike, the next exposure is in the railway 

 cut a mi?le east of Cochesett Station. The strata here dip from 5^ to 10° 

 N., and afford the following section from the top downward: 



Section east of Coeliesett Station. 



Feet. 



3. Conglomerate," pebbles of quartzite and smoky quartz 10 



2, Sandstone and arkose, gray 40 



1, SliaJe, blue and compact 10 



A thrust plane, with slickensides trending N.-S , was noted on one bed, 

 and there are to be seen small vertical quartz veins containing cavities lined 

 with botryoidal limonite. 



About a mile south of the Cochesett exposure, coal is represented to 

 have been found, in the area between the Hockamock and Town brooks.^ 

 The place of this bed would be at a depth of about 1,800 feet beneath the 

 Cochesett section. 



1 Edward Hitclicock: Report^ 1833, p. 277; Final Keport, 1841; p. 129, also on geological map. 

 C. H. Hitchcock : Geological map in Walling and Gray's Atlas of Massachusetts, 1871. 



