SMYENA-DANFORTH BRANCH. 81 



the river. The forest is so dense, however, that one could easily miss a 

 gravel system unless following it lengthwise. In T. 9, R. 5, several short 

 ridges of true glacial gravel are found a few miles west of the Masardis 

 River, and it is not impossible that they are part of a series extending past 

 St. Croix Lake to Smyrna. 



From near Smyrna Mills the gravel series takes the foi-m of a nearly 

 continuous and rather flat-topped plain of sand and gravel following the 

 east branch of the Mattawamkeag to Haynesville. In places the plain, 

 before being eroded by the stream, extended across the whole of the rather 

 narrow valley. The river sometimes flows at one side of the gravel plain, 

 but more often it has eroded the central part, thus being bordered on each 

 side by terraces of erosion. Sometimes it has cut out two channels, leav- 

 ing a central ridge uneroded. It will thus be seen that the alluvium con- 

 tained in the narrower parts of the valley presents the external features of 

 ordinary valley drift. The material of this alluvial plain is in general 

 composed of sand and fine gravel, but with a mixture of larger pebbles, 

 cobbles, and some bowlderets. The stones are much rounder than those 

 found in the beds of the other streams of this region, and must have been 

 subjected to much greater attrition. In some places the valley broadens 

 considerably. Here the gravel plain does not widen correspondingly, so 

 as to fill the whole valley, but sometimes is bordered on the side away from 

 the river by a steep bank downward, which, so far as I could determine, is 

 not due to erosion. The alluvial plain of highly rounded matter is thus 

 shown to be of glacial origin, and not a plain of ordinary river drift. Its 

 breadth vai-ies from a few rods to about one-fourth of a mile. This plain 

 is a good instance of what I have elsewhere named the osar-plain, or broad 

 osar. 



Not far north of Haynesville this sei'ies is joined by another series, 

 from Island Falls. At Haynesville the gravel forms a single plain about 

 one-eighth of a mile broad, which shows that the two tributary glacial 

 rivers here flowed as one. The two branches of the Mattawamkeag River 

 also unite not far north of Haynesville to form the main river. The river 

 here flows in a broad and quite level valley. For 4 miles southeast of 

 Haynesville an osar-plain of sand and gravel extends along the axis of the 

 valley, bordered by a plain of horizontally stratified sand and silt, one-half 

 mile or more wide. In many places this sand has blown into low dunes. 

 MON xxxiv 6 



