256 GEOLOGY OF THE NARRAGANSETT BASIN. 



third of a mile distant. This exposure, along the western road, is very- 

 interesting on account of the extreme lengthening and flattening which 

 many of the pebbles have undergone in consequence of shearing. The 

 pebbles consist of quartzite and granite. Those of larger size, embedded 

 in the softer cement, have been less sheared and can be more readily recog- 

 nized. The basal conglomerates continue to be shown along the western 

 side of the road to Knightsville, resting toward the south upon granite, 

 and farther north upon schists. Where the basal series fails to be exposed, 

 the western border of the Carboniferous area can still be recognized by the 

 steep hillsides formed by the older pre-Carboniferous rocks. 1 



EOCKS EAST OF THE WESTERN BOEDER OF THE CARBONIFEROUS 

 AREA IN WARWICK AND SOUTHERN CRANSTON. 



The basal series of rocks are quartzitic sandstones of white color. 

 Overlying them are bluish sandstones and coaly shales. The coaly shale 

 east of the great bend in the western border of the Carboniferous area 

 northwest of Natick has already been mentioned. At the northern end of 

 the village, along a connecting road west of the river, blue sandstone with 

 darker courses, and a few conglomerate layers with small pebbles, are well 

 exposed. Strike N.-S., dip 45° E. A sharp change in the strike must 

 take place in Natick, as alreadj^ indicated in connection with the description 

 of the border line. 



Along the road from western Pontiac northward a number of expo- 

 sures occur. They indicate the presence of bluish sandstone, with small 

 pebbles, and bluish-black ottrelitic shaly rock along the western side of the 

 hill east of the New York, New Haven and Hartford Railroad. The strike is 

 northerly and the dip 10° E. The entire hill and the valley on the west 

 is probably underlain by an alternating series of blue sandstones, often with 

 conglomeratic layers and bluish-black or black ottrelitic shales. Coaly beds 

 are common on the east side of this line of hills, and were formerly mined 

 farther northward, at the well-known mines northeast of the Reform School 

 on Sockanosset Hill, on the east side of Rocky Hill, which geologically 

 is a continuation of Sockanosset Hill, and still farther northward in the 

 Valley Falls district. This series of coaly rocks not far above the base of 



1 Iu my opinion this cliff is not an old shore escarpment, but is due to the deformation of the old 

 floor of the basin and the subsequent erosion of the soft .beds which lie against it. — N S. S. 



