626 H. L. FAIRCHILI) POST-GLACIAL UPLIFT OF NEW EXGLAXD 



(2) The zone of the wave attack was constantly shifting during the 

 rise ont of the sea. 



(3) The inhibiting effect of sandy slopes (77, page 301) and cf 

 boulder-studded surfaces was considerable. However, we do see evi- 

 dence of erosion that was not done at the present land level. The 

 valleys in Truro and AVellfleet across the belt of land are apparently the 

 effect of marine erosion. 



liHODE ISLAXD 



The summit level of the Blackstone Eiver has been described. Exam- 

 ination of the valley below Saundersville will find the inferior plains. 

 The city of Providence is built on the lowest plains, mostly less than 

 100 feet altitude. 



The theoretic figures for the Providence quadrangle are 295 feet for 

 the northwest corner and 255 feet for the southwest corner. The city 

 of AYoonsocket lies just over the northwest corner and on the Burrill- 

 ville quadrangle. Southeast and south of the city is a handsome gravel 

 plain Avith altitude 290 feet. This is reached by the electric railway 

 leading to Providence. The south edge of the plain is a mile south of the 

 city, at the junction of Park Avenue and Smithfield Street, where the 

 railway has an excavation for gravel. The plain is here utilized for a 

 race-track. The plain extends northeast, abutting against wave-washed 

 rock slopes. Xorthward it becomes irregular in surface, of varied com- 

 position and including boulders. It is a typical outwash plain, laid at, 

 practically, the marine summit. 



At the southwest corner of the Providence quadrangle lies another 

 excellent sandplain, at near the marine summit. Two miles west of 

 Knights ville the west-leading road climbs by a cut to the so-called 

 "Dugaway" hill and for a mile lies oji a level plain. The altitude is 

 210 feet, representing perhaps 15 feet of submergence. The plain ter- 

 minates westward against a rocky morainal slope on the edge of the 

 Burrillville sheet, where a cliff, bare ledges, and a boulder field mark the 

 shoreline. 



The Xeutaconkanut Hill and Park, a mile west of Olneyville, is an 

 example of a wave-washed hill. The bare rock summit is 260 feet, just 

 about the summit water level. The drift has been swept off' and rinsed 

 down the slopes. Almost no foreign stones remain on the east and south- 

 east side, where exposed to heavier storm waves, but on the sheltered 

 slopes foreign boulders are piled with the native rocks. 



^lany inferior plains are noted in the Providence district. The north 

 l)art of Olneyville has been widely excavated for gravel up to 180 fee-'. 



