300 SURFACE GEOLOGY. 



represented by a few fine examples, as Fort hill in Lowell, on the east side of Concord 

 river; Forest hill at the south-east edge of Dunstable, with another close north-east; 

 and Blanchard's hill, with two others at the north-east, situated near the north line of 

 Dunstable, west of Salmon brook. They are wanting in Pepperell and Townsend ; but 

 a prominent one is crossed by the east line of Ashby north of Lock's brook, and they 

 are quite numerous in the next ten miles to the west. 



In Groton and Ayer, lenticular hills are well shown along the east side of the Worces- 

 ter & Nashua Railroad. Thence to the south-west they are rarely seen till we reach 

 Worcester, where they are again abundant, especially for three or four miles north and 

 west of the city, varying from 50 to nearly 200 feet in height. Reservoir or Chandler's 

 hill, Newton, Prospect, and McFarland's hills are good examples. 



Westward from Ayer along the Fitchburg Railroad, they occur at Shirley station, in 

 the south part of Lunenburg, and prominently north and north-west of Leominster. At 

 Fitchburg, and for several miles to the west and north-west, all the hills are ledgy with 

 no important accumulations of till. Their notable abundance in New Ipswich and 

 Rindge continues into Ashby and the north part of Ashburnham ; but the next five 

 miles to the south and south-west showed very few lenticular hills. 



In Gardner, they again become numerous and prominent, Cowee's and Parker's hills 

 being very conspicuous examples. From their tops as many as twenty of these hills 

 are visible, mostly within two or three miles. Parker's hill is separated by a hollow of 

 about 40 feet from a contiguous lenticular hill that rises at about twenty-five rods north- 

 east to a nearly equal height. At the bottom of this depression, which is 100 feet above 

 the foot of the hill in each direction, a former water-course, fifteen to thirty feet wide 

 and four or five feet deep, filled with boulders from among which all the earth has been 

 swept away, extends from north-west to south-east twenty rods or more. Its explana- 

 tion seems to be, that while the ice-sheet was melting over this area, portions remain- 

 ing at the north-west side of the hill turned a stream through this gap. 



On Plate xviii of the second volume of this report. Prof. Hitchcock has shown the 

 position of prominent lenticular hills in Bernardston and the north part of Gill. He 

 also reports their occurrence in the north part of Montague ; in Amherst, where Mt. 

 Pleasant, other hills at the north and north-east, and the College hill are examples, also 

 the hills in the south part of the town, called Castor and Pollux; in South Hadley, 

 Prospect hill near the Seminary being of this class ; and in the west edge of Granby. 

 The trend of these hills in the north part of Middlesex county is between south and 

 south-east ; about Worcester, Gardner, and Amherst, it is nearly north and south ; 

 while in Bernardston and Gill it is commonly a little to the west of south. Probably 

 lenticular hills cccur at many other localities in this state, which has been specially 

 explored for this report only in its north-east portion shown upon our map. 



Cape Cod and Long Island. A hasty journey has been taken upon Cape Cod and 

 Long Island, with a hope that some examination of the drift deposits near their south- 

 ern limit might lead to a better understanding of the various questions suggested by 

 exploration in New Hampshire. The description of Plymouth and Barnstable coun- 



