236 SURFACE GEOLOGY. 



surface of a glacier now. It is the contact of the more limited phenomena of the local 

 glaciers which succeeded this all-embracing winter (their lateral, frontal, median, and 

 limited ground moraines and their erratics), with the more wide-spread and general 

 features of the drift that I have been able to trace in the White Mountains this summer. 

 The limits of this paper will not allow me to do more than record the general facts, but 

 I hope to give them hereafter more in detail, and with fuller illustrations. The most 

 difficult part of the investigation is the tracing of the erratics to their origin ; it is far 

 more intricate than the identification of the origin of ordinary drift, or of continuous 

 moraines, because the solution of the problem can only be reached under favorable 

 circumstances, where boulders of the same kind of rock can be followed from distance 

 to distance, to the ledge in situ from which they were detached. Now, in the neigh- 

 borhood of the White Mountains, we find, beside the typical or northern drift, large 

 erratic boulders, as well as lateral, frontal, and median moraines. A careful examina- 

 tion of these shows beyond a doubt that they came from the White Mountains, and 

 not from the northern regions, since they overlie the typical drift which they have only 

 here and there removed and modified. A short description of the facts will leave no 

 doubt upon this point. 



The finest lateral moraines in these regions may be seen along the hillsides flanking 

 the bed of the south branch of the Ammonoosuc, north of the village of Franconia. 

 The best median moraines are to the east of Picket hill* and Round hill. These lat- 

 ter moraines were formed by the confluence of the glaciers which occupied the depres- 

 sion between Haystack and Mt. Lafayette, and that which descended from the northern 

 face of Lafayette itself. These longitudinal moraines are particularly interesting as 

 connecting the erratic boulders on the north side of the Franconia range with that 

 mountain mass, and showing that they are not northern boulders transported south- 

 ward, but boulders from a southern range transported northward. But by far the most 

 significant facts showing the great extent of the local glaciers of the White Mountain 

 range, as well as the most accessible and easily recognized, even by travellers not very 

 familiar with glacial phenomena, are the terminal moraines to the north of Bethlehem 

 village, between it and the northern bend of the Ammonoosuc river. The lane start- 

 ing from Bethlehem street, following the cemetery for a short distance, and hence 

 trending northward, cuts sixteen terminal moraines in a tract of about two miles. 

 Some of these moraines are as distinct as any I know in Switzerland. They show un- 

 mistakably by their form that they were produced by the pressure of a glacier moving 

 from 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 de- 

 scent. The steeper slope of a moraine is always resting against the glacier, while the 

 outer side is comparatively little inclined. The form of these moraines, therefore, as 

 well as their position, shows that they have come down the Franconia mountains. A 

 few details concerning their location may not be out of place, in order that any visitor 



* Since called Mt. Ag.ossiz.— C. H. H. 



