THE NE WTONVILLE SAND-PLAIN. 8 1 1 



been confined and concentrated in their derivative action, and likewise con- 

 strained so as to heap their material into tumuli, whose location was deter- 

 mined by the constraining agency more than by any feature of the local 

 topography or other present condition." 1 



That some kames are moulin-kames seems to be undoubted, 

 and perhaps we may best picture to our minds their formation 

 by turning an hour-glass and watch the sand heap itself up. A 

 certain amount of stratification will take place in air, which would 

 be increased when the air is replaced by water. 



10. Shore-li?ie. — With the working hypothesis that this sand- 

 plain was formed in a body of standing water, I reached the con- 

 clusion that it was at the head of an estuary. With the existing 

 topography to the south it is almost impossible to conceive of 

 the water as having been enclosed. Such a pond would require 

 too many dams not now existing. If one accepts the delta front 

 as proof of a body of standing water, he seems forced to con- 

 clude, on looking over the ground, that the Newtonville sand- 

 plain was built in an arm of the sea. If so, the estuary must 

 have connected with the Atlantic along the present course of 

 the Charles river and through Mother brook to the Neponset. 

 It must have had a very temporary shore-line at any given level, 

 as there is hardly a trace of it now on the till-covered slopes, 

 except in one place on the east bank of the Charles river, about 

 a mile southeast of Newton Upper Falls where Dr. T. W. Harris 

 found a faint cliff, as if made by shore cutting, with a long, 

 gently shelving slope below it. In representing this shore-line 

 on the second model, I have tried to show no beach effect, but 

 to indicate that the land was but recently submerged, and that 

 the water conformed to the contour of the till-covered slopes. 



11. Relation to other sand-plains. — The intimate connection 

 between the Newtonville sand-plain and the one immediately to 

 the north of it, branches of the same esker running to each, sug- 

 gests a connection of this bit of the history of our New England 

 ice-sheet with other portions. Were the Auburndale sand-plains 

 formed before or after the Newtonville ? What other esker 



'Am. Jour, of Sci., 1884, p. 381. 



