THE BUCKLAND LAKE. 603 



easily tollowed to tliis point aiul not fai-ther. It maintains a level about 

 200 feet below the Ashtield Lake and 100 feet above the Deei-field River 

 terraces. 



It is clear that after filling this lower valley for a long time and allow- 

 ing the waters to transport the great body of sand into the Ashfield Lake the 

 ice retreated north to Buckland Center and stood there for a time (b"), 

 maintaining a lake of great depth, which still drained through the narrow 

 canyon and across the sands of the Ashfield Plains, producing the excep- 

 tionally large amount of erosion of these sands, while the sands advancing 

 along its own bottom were checked when the waters passed into the narrow 

 gorge, and were ckopped so suddenly that a steep, submerged delta front 

 was formed. Exactly this has been happening now for several years at 

 Millers Falls, where, to improve the railroad, the river above has been 

 turned into a new course for a distance through deep sands, and has thus a 

 great amount of material at its disposal, and a broad, flat bai- extending 

 across stream is creeping down into the deep Avater above the dam, pre- 

 senting a shai-ply sloping delta front to the obstructing dam, as do the 

 sands here to the obslrueting gorge. 



At their south end these lower sands are at first fine grained, well sorted, 

 cross bedded, and undisturbed; northward they are soon changed to coarser 

 sand, the surface becomes pitted with kettle-holes, and the sands grow coarser 

 and become coarse gravel. At last glacial bowlders are intermixed and 

 the sand is twisted and tortuous in stratification, and it seems almost to 

 grade into till, as if bowlders were cairied south with masses of ice by 

 the waters and mingled with the sands, or as if the ice itself had advanced 

 with many oscillations and disturljed the sands (b"). 



The ice here postulated (b") was a lobe sent southward from ice 

 which then filled the Deerfield River Valley and much of the high ground 

 north of the river. Another lobe in'ojecting southward in a much shorter 

 valle}-, and one rising very rapidly to the high level, produced another con- 

 siderable accumulation of sand in the extreme northeast corner of Hawley, 

 at the headwaters of Ruddock Brook, which passes down the valley of 

 Clessons Brook to join the sand described already as extending south 

 from Buckland Center up the same brook. They join at the south line of 

 the town (at Buckland Four Corners), and run across Ashfield to the delta 

 front described above. 



