272 J. W. GOLDTHWAIT GLACIATION IN THE WHITE MOUNTAINS 



appears to have been determined by the east-west trend of the ice-front 

 at the time it built the northernmost line of moraine. 

 Agassiz reported that 



"the moraines show unmistakably by their forms that they were produced by 

 the pressure of a glacier moving from the south northward. This is indicated 

 by their abrupt southward slope facing, that is, toward the Franconia Range, 

 while their northern face has a much gentler descent. The steeper slope of a 

 moraine is always resting against the glacier, while the outer side is compara- 

 tively little inclined. The form of these moraines, therefore, as well as their 

 position, shows that they have come down the Franconia Mountains." M 



Regarding this, I can only say that when the whole territory in ques- 

 tion is examined one finds steep slopes as often on the northern sides of 

 the morainic ridges as on the southern sides ; in fact, were I compelled to 

 express an opinion as to the prevalence of steep slopes on one of the two 

 sides, I would say that they were to be found more often on the north. 



STRUCTURE OF THE MORAINE 



The most striking feature of the Bethlehem morainic belt is the abun- 

 dance and great size of the blocks which lie on its surface. At first sight 

 one suspects that there are ledges close beneath, which have furnished the 

 ground moraine with an overabundant supply of newly quarried rock. 

 The aspect resembles that of granite ridges, where ice-borne blocks and 

 glaciated outcrops share a large part of the surface. The utter absence 

 of ledges, however, is soon realized, and at the same time one finds to his 

 surprise that beneath the block-strewn surface there is not ground mo- 

 raine, but stratified drift. Excavations by the roadside in many places — 

 most of them shallow, but a good many of them 10 or 15 feet deep — prove 

 beyond a doubt that the morainic ground is chiefly composed of sands, 

 gravels, and cobbly boulder beds, with the finer sediment predominating. 

 Locally, till containing ice-worn stones composes the knobs and swells; 

 but this is exceptional. Although Upham reported that the deposits were 

 composed of till, extensive road construction of the last five or ten years 

 has stripped the moraine of its disguise and revealed it as essentially a 

 kame moraine belt. This, to my mind, is significant; for such a condi- 

 tion would be more easily accounted for by the retirement of the front of 

 the Canadian ice-sheet northward and westward from the Ammonoosuc 

 Valley — which drains in that direction — than by the retirement of the 

 front of a local White Mountain ice-cap southward to the foot of the 

 mountains. The Canadian ice-sheet, with its front covering the north- 

 ward bend of the Ammonoosuc between Bethlehem Junction and Little- 



u Op. cit, p. 164. 



