110 



GEOLOGY OP THE NARRAGANSETT BASIN. 



monograph. Lingulse (now Obolus, see p. 113) were found in a pebble in the 

 red Carboniferous conglomerate on the east bank of Abbots Run, between 

 Lanesville and Arnolds Mills, Rhode Island. Eastward an Obolus pebble 

 was found on the beach near Marshfield, Massachusetts, together with a 

 large fragment of quartzite carrying the long, parallel, closely set burrows 

 of Scolithus linearis. Both of these fragments were within the nossible range 



Fig. 5.— Sketch map of distribution of upper Cambrian pebbles. The north-south lines represent the supposed direction 

 of glacial motion during the maximum development of the New England glacier. 



of glacial stream drift from the northeasternmost outcrops of Carboniferous 

 conglomerate in the main basin. 



In July, 1895, I found a small sand-blasted Obolus pebble on the cliff 

 near Highland Light in Truro, at the northern extremity of Cape Cod; and 

 another pebble, carrying the same brachiopod, was found in an ancient 

 beach on the ocean side of Provincetown. These pebbles are so far to the 

 east of the known Carboniferous conglomerates on the mainland that their 

 derivation from the main basin or from the Norfolk Basin seems improbable, 

 particularly for the reason that the movements of the glacial currents and 



