GEOLOGY. 231 



layers of thin pine wood, of equal thickness, each thickness repre- 

 senting 500 feet, the whole thus displaying to advantage the 

 contour lines obtained in the survey. The outcrops of the various 

 rock formations were indicated by appropriate colors. Prof. 

 Hitchcock advanced certain views with regard to the anticlinal or 

 synclinal character of the ridge, which were at variance with the 

 generallv received ideas. Mt. Washington has been regarded as 



^j *j ^j 



synclinal in structure, but Professor Hitchcock regards it as an 

 inverted anticlinal. One of the points on which he bases this 

 opinion is the fact that on the eastern side of the mountain occur 

 strata which for some distance follow in their dip the slope of the 

 mountain and then suddenly dip away into the mountain. If the 

 professor's views as to the anticlinal structure be correct, it will 

 be necessary to suppose that the folding force came from the land 

 side and not from the ocean. 



In connection with the State Geological Survey of New Hamp- 

 shire, a party of scientific men are spending the winter (1870-71) 

 on the top of Mt. Washington, to make various meteorological 

 observations. 



Local Glaciers of tlie White Mountains. At the Troy meeting 

 of the American Association a paper by Professor Agassiz on this 

 subject was read by Professor Perry. Agassiz said that in 1847 

 he had noticed unmistakable evidence of the former existence of 

 local glaciers in the White Mountains of New Hampshire, but 

 that he had had no opportunity to make a careful examination of 

 the ground until the present summer (1869). He now asserts 

 that the drift so called has the same general characteristics on the 

 northern and southern sides of the White Mountains, and that 

 whatever, therefore, may have been the number of its higher 

 peaks which at any given time, during the glacial period, rose 

 above the great ice-sheet which then covered the country, this 

 mountain range offered no obstacle to the southward movement 

 and progress of the northern ice-fields. 



After describing the characteristic marks of glacial action and 

 the various kinds of moraines, and showing that the typical drift 

 was one ground moraine, he says : 



" 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 prob- 

 lem can only be reached under favorable circumstances where 

 boulders of the same kind of each can be followed, from distance 

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

 No\v, in the neighborhood of the White Mountains we find, beside 

 the typical or northern drift, large erratic boulders, as well as 



