DIGHTON CONGLOMERATES. 185 



In this northern part of the basin the several exposures of conglomerate 

 referred to the Dighton group lie in the inner or upper part of synclines. 

 This is true of the Great Rock area in Rehoboth, whence the rocks extend 

 eastward to "Rocky Woods," near Taunton. Another, and perhaps the 

 best area, is that of the Dighton sjiicline, extending from Dighton into 

 Swansea. Another well-defined syncline in which these beds are found 

 forms Ides Hill, west of Attleboro village. The coarse conglomerates at 

 Purgatory and Paradise rocks, in synclines near Newport, resemble the 

 rocks of this horizon. 



The outcrops of coarse conglomerates at Swansea Factory and imme- 

 diately west appear locally to strike northwest and dip north, indicating 

 either that the great syncline is overturned southward or that there is here a 

 local folding along the northern side of the major synclinal fold. Outcrops 

 are too few to verify either hypothesis, but the high inclination of the 

 observed strata southward below the Dighton group shows that the beds on 

 this northern side of the synclinal axis stand at much higher angles than 

 do those on the southern side. The Great Meadow Hill syncline is nearly 

 symmetrical, but the Attleboro syncline on the north is unsymmetrical, 

 with vertical dips on the south side of the axis. 



The Dighton conglomerate is composed mainly of grayish and green- 

 ish quartzite pebbles in the southern areas; toward the north, as in the 

 Attleboro area, it is equally rich in granitic pebbles. The amount of 

 quartzite in this group must represent several hundred feet of strata 

 stripped off the adjacent country in Carboniferous times. Many of the 

 pebbles are fossiliferous, carrying the upper Cambrian fauna already 

 described. The pebbles vary in size from a fraction of an inch to rounded 

 waterworn cobbles a foot in diameter. The reduction to spheroidal shapes 

 apparently indicates their passage through the surf line on a beach. (See 

 PI. XIII.) 



In many sections the pebbles are packed together with the pellmell 

 structure of glacial till; the paste is often earthy and ferruginous, and 

 when slightly attacked by weathering allows the pebbles to roll out; in 

 other sections pebbles and paste are thoroughly cemented, so that the rock 

 breaks up only along joints. 



Now and then a pebble shows a joint recess where the rolling action 

 did not continue long- enough to reduce it to the form characteristic 



