620 H. L. FAIKCHILD POST-GLACIAL UPLIFT OF XEW EXGLAND 



J3aker Brook Valley, where the submerged plains of line material are 

 conspicuous at about 390 feet. Southeast of the city, toward South 

 Fitchburg, the valley, some three-fourths mile ^vide, was entirely filled 

 with gravel, the benches on the valley sides being 390 feet and over. 

 The Saint Bernard Cemetery is on a rolling gravel plain at 412 to 415 

 feet, which is probably a remnant aggraded above the estuary level. On 

 the Duck Mill road, just below the railroad, a bench of coarse gravel is 

 excavated at 3t)0 feet. Excellent plains lie along the Mack road parallel 

 with the railroad. Bakers Pond lies in a broad, lower plain with height 

 370 to 380 feet. The summit of the gravel deposits is seen both north 

 and south of Youngs road, east of the pond, with altitude up to 410 feet. 

 Four miles southeast of Fitchburg the city of Leominster is on tho 

 delta of Monoosnoc Brook at about 390 to 400 feet. Leaving the Xorth 

 Xashua Eiver at Xorth Leominster and passing east to Ayer, evidence of 

 standing water is common at elevations below 390 feet, in smoothed sur- 

 faces and detrital j^lains. At higher levels are kames and glacial de- 

 posits. At Shirley are wide plains of inferior level, about 280 feet, and 

 at Ayer at 240 to 260 feet. Much of the area of Camp Devens is roll- 

 ing sandplain at 260 to 340 feet. The divide east of Ayer, between 

 Xashua and Merrimac drainage, is only 260 feet. 



UPPER XASHUA VALLEY, CLIXTOX DISTRICT 



The upper part of the Xashua A'alley, in the towns of Boylston, We>t 

 Boylston. and Clinton, is the only valley in eastern Massachusetts with 

 such northward direction and high altitude as to hold glacial lake waters. 

 Crosby has well described the district and the glacial features (58). 



TTith the ice barrier on the north and west, the early escape for the 

 impounded water was by the channel one and one-fourth miles south 

 of Boylston Center (on the west edge of the Marlboro sheet), which 

 leads south to Quinsigamond-Blackstone drainage. The altitude of this 

 pass is 440 feet, by the map, being about 80 feet over the theoretic marine 

 level. The next lower pass is two miles south of Clinton village, lead- 

 ing east to the Assabet-Concord drainage, with map altitude of 350 feet. 

 Crosby makes this pass, which he calls the ^^South Dike'^ outlet, 365 to 

 375 feet, which is as high as the marine plane at this point. Even with 

 this height it would carry outflow, the escape of Crosby's Clinton stage- 

 of the Xashua glacial waters (58, page 318). The next lower pass is 

 at Ayer, with altitude only 250 to 260 feet, and it was droT\^led under 

 140 feet of standing water. 



The prominent sandplain two miles north of Boylston Center, with 



