270 GEOLOGY OF THE NAKRAGANSETT BASIN. 



inches long, similar in character to the pebbles in the Dighton conglomerate. 

 The granite from which the arkose and kaolin were derived was too decayed 

 to furnish pebbles, but the quartzitic rocks withstood weathering sufficiently 

 to furnish good pebbles to the basal conglomerates, in spite of probably 

 long transportation. 



FALL RIVER. 



A still more interesting exposure occurs in Fall River, in Annawan 

 street, halfway down the hillside, behind some mills. The eastern border 

 of the present Carboniferous area extends from Steep Brook along the 

 escarpment bordering Taunton River to this locality in Fall River, with a 

 trend of about N. 32° E.; southward to Townsend Hill its trend is N. 40° E. 1 

 In the angle a considerable exposure of the overlying Carboniferous rocks 

 is preserved. Behind the mill on Annawan street the arkose rests directly 

 upon the granite or is separated from it only by a thin course of coaly 

 shale. The contact is well shown. Arkose layers, composed chiefly of 

 angular quartz grains derived from the granite, alternate with coaly shale 

 layers. Northward toward the railway tunnel under the next street, the 

 alternation of arkose and coaly shale layers continues, the arkose changing 

 to a gritty sandstone; the coaly slate then forms a considerable exposure, 

 overlying the arkoses, and constituting the steep wall of the hillside as far 

 as the railway track; strike N. 50° E., dip 40° W.; farther south, strike 

 N. 30° E. Fern impressions occur in the shales. West of the railway track 

 occurs a gritty sandstone. 



TOWNSEND HILL. 



Two and three-fourths miles southwest of the exposure in Fall River 

 occurs the exposure on the west side of Townsend Hill. Granite forms 

 the hillside down to the 100-foot contour. Below, where a small bench 

 occurs, forming a northerly projection on the hillside, the arkose is exposed. 

 The actual contact with the underlying granite is not seen, the stratigraphic 

 interval being about 5 feet. 



1 The existing escarpment seems to me to be due to the deformation of the granite formation of 

 the basin and the subsequent removal of the softer stratified beds. If the Carboniferous shore lay 

 along this line, it was there but for a short time during the progressive overlapping of the accumu- 

 lating basal sediment. — N. S. S. 



