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SCIENCE. 



[Vol. XX. No. 514 



SCIENCE: 



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THE GREEN MOUNTAINS' ANTICLINAL. 



BY O. H. HITCHCOCK, HANOVER, N.H. 



The key which is to unlock the intricacies of New England 

 geology is to be found in the discovery of the proper structure of 

 the Green and Hoosac Mountains. Hence in the occupation of 

 this field for careful investigation the United States Geological 

 Survev has acted wisely; and one cannot restrain impatience with 

 the officials of the printing office, who have haJ the completed 

 manuscripts descriptive of these results in their hands for more 

 than two years, and liave not published them. 



The pioneers of American geology refen-ed this Green Mountain 

 range to the " Primary" series, chiefly because, in their view, all 

 foliated crystalline rocks belonged there. Of course any sections 

 illustrative of their notions from the theoretical standpoint would 

 exhibit the anticlinal structure. But their actual illustrations, 

 compiled from observation, do not support their theory; as shown 

 by C. T. Jackson's section across the White and Green Mountains, 

 and E. Hitchcock's sections across the Hoo-ac Mountain. Hence 

 it was that the geological literature of thirty and forty years' stand- 

 ing is pervaded with extreme applications of metamorphism. C. B. 

 Adams in the second report upon the geology of Vermont, in 

 1846 (p. 166) raised the query whether the occurrence of the 

 quartz rock, limestone, and talcose schists upon the east side of 

 the Green Mountains, in Plymouth and elsewhere, did not include 

 the repetition of the Taconic rocks over an azoic foundation. He 

 offered this suggestion as something worthy of investigation. 

 His successors in the study of Vermont geology attempted to dis 

 cover the structure of the mountains, as well as of all parts of 

 the State, by measuring thirteen sections across the territory from 

 east to west. A summary of the results was given by E. Hitch- 

 cock in the final report, page 353; from which it would appear 

 that the structure of the Green Mountains was anticlinal. His 

 contemuorary, Logan, insisted that this structure was synclinal. 

 The later studies of the writer, in several publications, confirm 

 the first view, which is also held by SeUvyn, the successor of 

 Logan as director of the Canadian Geological Survey. 



Having had occasion recently to examine the rocks of Hoosac 

 Mountain and the neighborhood, the writer desires to offer the 

 following observations. The excavation of the Hoosac tunnel 

 has afforded us the opportunity of observing the structure of the 

 interior of this mountain compared with what may be seen at the 

 surface; and it was stated in Macfarlane's Railway Guide, 1879, 

 that Hoosac " Mountain is believed to be an inverted and very 

 much crushed anticlinal." Professor R. Pumpelly, in his paper 

 upon secular rock disintegi'ation in the Bulletin of the Geological 

 Society of America, vol. II. , presents a map covering a part of this 

 mountain, which shows the distribution, first, of a central core 

 of granitoid gneiss; second, a coarsely foliated, often white, 

 gneiss, supposed to be the dynamic product of a Cambrian con- 

 glomerate; third, the Hoosac schists, which wrap around and over 



the gneisses; and, fourth, the quartzite, which is the basal mem- 

 ber of the Cambrian known familiarly as the "granular quartz" 

 of Emmons. The anticlinal fold is therefore easily recognized. 

 The granitoid gneiss in the centre crops out upon the mountain 

 a mile or so south of the tunnel, and the arch dips ten degrees 

 northerly, and the rock is exposed where cut by the excavation. 

 It is made up of blue quartz, large microcline crystals, somewhat 

 elongated and assuming the augen habit, together with the green- 

 ish mica, chlorite, and epidote of the foliation. It is said to be 

 the equivalent of the gneiss of Clarksburg Mountain. The Ver- 

 mont geology described this rock as the Stamford granite (gneiss), 

 and speaks of it at several places farther north also. Our New 

 Hampshire studies enable us to correlate this central granitoid 

 augen gneiss with the " porphyritic granite, or gneiss," said tO' 

 lie at the foundation of the stratigraphical column. In New 

 Hampshire the mica is commonly biotite, while the greenish 

 micas at the tunnel are more suggestive of the later protogene, 

 called " Bethlehem gneiss." As the chloritic mineral is the result 

 of alteration, its presence is not definitive. But the augen gneiss 

 seems to constitute the foundation upon which the later gneisses 

 were disposed in both localities. 



There must be a decided unconformity between the augen and 

 the overlying white conglomerate gneiss. This is shown not so 

 much by a decided divergence in the angle of dip as by the gen- 

 eral principle that a conglomerate is necessarily unconformable 

 to the original rock from which the fragments have been derived. 

 Some would say the augen gneiss was of igneous origin; and, if 

 so, the discordance would be equally marked. 



This Hoosac gneiss, or its equivalent, must be manifested in 

 the Shelburne Falls anticlinal area, the Halifax-Reading ranges,, 

 and others farther east and north. Each range has the anticlinal 

 attitude, while the intervening basins are of newer rocks. Next to 

 the Green Mountains structure, the succession of gneissic waves 

 capped by hornblende schist have aided us in working out the 

 stratigraphy of the New England crystallines. 



The proper place for the Hoosac schists may be an open ques- 

 tion. E. Hitchcock, in his map of 1844, made the Gray lock,. 

 Hoosac (west side), and the Charlemont schistose areas equiva- 

 lents; and perhaps this is the most natural view. We must, how- 

 ever, remember that these hydro-micaceous and chloritic schists^ 

 are not confined to a single horizon. There are, first, those of 

 the Green Mountain gneiss, described as pre-Cambrian ; second,, 

 those of the granular quartz, or Lower Cambrian; third, those of 

 the Berkshire and Graylook terranes, as pointed out by Dale, and 

 con-esponding to the magnesian slate of Emmons. Hence there 

 may be reason for the reference of the Hoosac schists to any of 

 four different horizons that best explain the dips. 



The Stockhridge limestone is evidently repeated on the east side- 

 of the anticlinal at Plymouth, Vt. Whether it once extended 

 along the whole range and has been eroded, or is represented by 

 an equivalent terrane, or is wanting, remains to be discovered. 



BOTANY AT THE EXPERIMENT STATIONS. 



BY GEOKGE F. ATKINSON, BOTANICAL DEPARTMENT, CORNELL UNI- 

 VERSITY. 



A REMARKABLE stimulus to botanical investigation has been 

 given in the last few years through the opportunities offered by 

 the organization of botanical departments at the various State 

 experiment stations. The acquisition by the States of the con- 

 gressional fund has afforded means, hitherto possessed only by a 

 few favored institutions, for the purchase of the expensive appa- 

 ratus and libraries of technical works needed in modern biological 

 research. It also provides for the employment of men who de- 

 vote part or the whole of their time to original study and the 

 practical application of the results. The fund was designed not 

 only for the purpose of treating economic botany in a practical 

 way, but also for the purpose of pure science study, which in 

 many cases must precede any practical treatment. 



Studies of forage plants, of the improvement of sorts by the 

 selection of seed, cross-fertilization, the distribution and harmf ul- 

 ness of weeds, the relations of micro organisms to the fertility of 

 soils, besides many subjects appertaining more or less to horti- 



