232 GLACIAL GRAVELS OF MAINE. 



level on the top, but it is in a thickly settled region and the sui'face may 

 not be in its original condition. The margin shows on nearly all sides a 

 steep slope outward, and the strata dip correspondingly at the exposures 

 examined. The material of the plain is fine gravel and sand with some 

 thin layers of silty clay. At some of the excavations examined the sedi- 

 mentary matter rested directly on the solid rock, which has lost most of the 

 glacial strise and is sand carved and polished under the action of the glacial 

 streams. A broad ridge of glacial gravel begins a short distance north of 

 Stevens Plain and extends north to the Presumpscot River. Wells are 

 said to have been dug 80 feet in this ridge without passing through the 

 gravel. Between this ridge and the delta-plain in West Cumberland and 

 Falmouth, before described as lying along the northwestern base of Black 

 Strap Mountain, there is an interval of fully 4 miles. If the Gray- West 

 Cumberland gravel series has any extension it must be this ridge extending 

 north of Stevens Plain. The local deposits of subangular gravel on the 



south slopes of Black Strap 

 wd^^-S?§3!3?d>?5S\ „ Mountain are seabeaches so 



WffSS^^^^i-S^9MM^ Stevens Plain is prob- 



■?f i^^iS?g^Sv^^Bp^:|?a^ ably a marine delta. The 



FlCi. 23.— Lanrtsliii .it Braiiilmll Hill, Portland, n, a, old .surface, overlain .,.,-,. ,. 



with 6 feet of well-rounded gravel and cobbles, with some bowlderets. OUtward Or antlChuai dip 01 



the strata on all sides is probably due in part to the surf washing over 

 the top of the plain. The gravel is slightly coarser on the west side of 

 the plain. 



The next deposit of the system is found as a ridge or terrace formed 

 against the west end of Bramhall Hill in the western part of Portland. 

 The osar matter is here rather coarse, containing a large proportion of cob- 

 bles, bowlderets, and some bowlders, and most of them are considerably 

 rounded by water. Extensive landslides have taken place on this hillside. 

 Near the Boston and Maine transfer station a section was exposed a few 

 years ago that showed an old sod covered by several feet of well-rounded 

 gravel and cobbles. The roots of grasses and other plants could still be 

 distinguished. The same landslips have covered the fossiliferous marine 

 clays with the glacial gravel. The hills of Portland would be exposed to a 

 somewhat violent surf when the sea stood at their level. The waves have 

 washed away much of the glacial gravel from the hills at each end of the 



