AREAL DESCRIPTION 631 



retic marine level, it suggests wave erosion, but the long-time cultivation 

 of the hill makes the matter equivocal. Poplar Hill, three miles north 

 of Blackstone Hill, appears decidedly flat-topped, as if truncated, at 

 472 feet. The valleys of the district are partly filled with water deposits. 

 At Eockland, Eockport, and West Eockport the ground up to 300 

 feet is clearly wave-swept. A mile northwest of West Eockport an ex- 

 cavation on the slope shows an outwash delta at 290 to 300 feet. 



Glacial Lake Plains 



Below the summit level of the invading sea, indicated by the isobases 

 of the maps, glacial waters were impossible; above that level they could 

 and did occur. A few glacial lakes have been and will be briefly 

 described. 



The Warwick sheet, southeast corner, shows a wide valley-fllling south 

 of Orange, the village on Millers Eiver, northern Massachusetts. The 

 heavier lake deposits are in the southern part of the valley, south ot 

 Eagleville. The outlet was southward by the passes, now under 580 feet. 



The glacial waters of the IN'ashau. Valley, described by Crosby (58), 

 have been referred to, page 620. 



A local glacial lake was held in the Chepachet Valley, in Ehode Island 

 (Burrillville quadrangle). The valley has a long stretch declining 

 northward, which favored ice blockade. The Acote Hill, close to Che- 

 pachet village, and famous as the fort in the near-battle in the Dorr Ee- 

 bellion, 1842, is a wave-leveled hill of gravel with altitude 500 feet, now 

 carrying the village cemetery. The point of hill on the south shows 

 similar planing. This stage of the Chepachet Lake apparently had its 

 outlet by a channel a little over a mile east of Acote Hill. 



The capacious Narragansett Valley held a lingering lobation of the 

 waning glacier which probably blocked the drainage from the west in 

 the Providence district. Sandplains so far above the marine level that 

 they may be attributed to glacial waters have been seen at Greenville, 

 TsTorth Scituate, and east of Coventry. 



A fine stretch of sandplains lies in the basin of the southwest branch 

 of the Pawtuxet Eiver, between Coventry and Washington (Kent sheet). 

 The plains form the north bank of the Flat Eiver reservoir. They were 

 built of detritus carried in by several south-flowing streams and are 

 outlined by the contour of 260 feet. This is only about 10 feet higher 

 than the marine level indicated on the map, and it is possible that these 

 plains correlate with the sealevel waters. 



XLIII — Bull. Geol. Soc. Am., Vol. 30, 1918 



