130 



THE FARMER'S MONTHLY VISITOR. 



miles to the south of then- native bed. This rock 

 coutimies on this sectional line, about tliree miles 

 west of Newbury, where it is replaced by niica 

 slate, which continues to Claremont. It is gen- 

 erally veryiniich contorted and filled with quartz 

 veins. At the Sii.ear River Falls, the strata dip 

 a little to the E. of S., and run N. and S. In this 

 rock crystals of pyrites 1-2 inch square abound. 



Green Mt. in Claremont, is based oil mica 

 slate ; it consists of quartz rock, which has the 

 appearance of regular stratification, but in real- 

 ity it is a crystalline structure, which divides the 

 rock into huge rhombohcdral fragments. 



On the side of this mountain in mica slate, oc- 

 cur large crystals of Staurotide of considerable 

 beauty. The micaceous slate on Twistback Mt., 

 is interstratified with small beds of impure blue 

 limestone. 



Near the centre of the town an excavation has 

 been made, with the expectation of finding iron. 

 The ore is oxide of manganese, with apocrenate 

 of iron and manganese, and is coutaiueJd in mica 

 slate. 



Sunapee Lake, which is about twelve miles in 

 length, is so near the summit level, that a slight 

 excavation would turn its waters either into the 

 Connecticut, or the Merrimack. It is elevated 

 about 1080 feet above the sea level, and the de- 

 scent of its outlet, Sugar River, to the Connec- 

 ticut is very rapid. 



The sections drawn by the aid of tlie Barome- 

 ter, which these outlines of their Geology are 

 designed to illustrate, are already drawn, and will 

 be published with the other sections andillustra 

 tiens in the final or General Report. 



LO.NGITCDINAL SECTION PARALLEL TO THE GEN 

 ERAL COURSE OF THE CONNECTICUT RIVER. 



While my Assistants were engaged in recon 

 noitering a series of sections which cross the 

 State in oblique directions, alternately transverse 

 and parallel to the general direction of the older 

 strata, I explored the first great longitudinal, and 

 a series of transverse sectional lines. The.iii-st 

 longitudial section runs in a North and South di- 

 rection, iiarallel to the general course of the Con- 

 necticut River, extending from Northfield in Mas 

 sachusetts, to Haverhill in New-Hampshire, and 

 passes over tlie principal rock formations of the 

 Western portion of the State. The ])rofile ot 

 this section represents the elevations and depres 

 sions of the country, and the manner in which 

 the rocks are disposed. It presents at one viev 

 the relative extent, direction, dip, and axes of el 

 evation of the strata, with their principal inclu 

 ded beds and veins. It is of an interesting char 

 acter, both in a scientific and practical point of 

 view, since it exhibits the junctions of the argi' 

 laceous slates and limestones with the older pr 

 mary rocks, and the changes which have been 

 effected in the former by the influence of the lat- 

 ter. Beginning at the Southern extremity of this 

 sectional line, I shall describe the outlines of the 

 Geological structure of the country which it in 

 tersects. 



Ill the town of Northfield, near the south-wes- 

 tern corner of the State of New-Hampshire, the 

 red conglomerates and sandstones of the valley 

 of the Connecticut River are seen reposing up- 

 on the argillaceous slate rocks of New Hamp- 

 shire : but the sandstone does not cross the State 

 line. 



The conglomerate and sandstone rocks of 

 Northfield consist of rounded pebbles and finer 

 particles of the primary rocks, such as granite, 

 gneiss, mica slate, quartz, and angular fragments 

 of argillaceous slate. These water-worn frag 

 ments arc cemented together by a paste of argil- 

 laceous and calcareous matter, and are colored 

 red by the per oxide of iron. The cement evi- 

 dently resulted from the abrasion and decompo- 

 sition of primary rocks, and was deposited by 

 water among the pebbles, and the whole was 

 subsequently indurated by the influence of heat 

 produced during the elevation of the primary 

 rocks. In several places, beds of granite are seer 

 protruding from beneath the sandstone. 



The conglomerates of Northfield and of Bor- 

 nardstown are represented, in Professor Hitch 

 cock's Geological Map of Massachusetts, as the 

 New Red sandstone, a rock which' overlies tl 

 coal measMres of Europe ; and at one time it w 

 supposed that coal might be found beneath the 

 sandstone of the Connecticut river. 



I am confident, however, that no coal w 



er be found in the rocks upon which the sand- 

 stone rests in this section of the State, lor they 

 do not belong to that formation. If the sandstone 



question should ultimately prove to be the New 

 Red, it must be considered as out of place; and 

 it may prove, like the tertiary, to have been de- 

 posited on any rocks that happened to be upper- 

 most at that epoch. Similar phenomena have 

 been observed on the continent of Europe and 

 country. Whovever examines the con- 

 glomerates and sandstones here described, will 

 perceive that the hard pebbles of quartz and gran- 

 ite have evidently been rounded by the action of 

 long continued currents of water, ^^'e may 

 therefore conceive that, iu ancient times, a pow- 

 erful river of much greater dimensions than the 

 present Connecticut pomed its waters tluoiigh 

 the highlands, and deposited the detritus of the 

 primary rocks of New-Hampshire, and the slates 

 and lime-stones of Vermont, in an estuary at that 

 time existing in the lower valley of the Connec- 

 ticut. The waters of such a river would have 

 been able to transport these loose materials to 

 their present localities, the coarser pebbles being 

 left where the current was rapid, while the finer 

 particles were deposited in those wide valleys 

 where the current must have been quite moder- 

 ate. That the waters of the Connecticut once 

 occupied a much higher level is incontestible, 

 since we have akmg its whole course regular ter- 

 races of aqueous deposition far more elevated 

 than the waters ever rise in modern tunes, du- 

 ring the most powerful (reshets. Ancient water- 

 marks are also observed abundantly on the rocky 

 ledges, at a considerable elevation above the 

 present bed of the river. That the sea entered 

 the valley of the Connecticut in former times, ha: 

 been most fully proved by the interesting re 

 searches of Professor Hitchcock and others, wli( 

 have examined the deposits of finer slates and 

 sandstones iu the lower valley, which contain 

 impressions of fishes and the foot-prints of wa 

 ding birds of gigantic size. All the facts discov 

 ered tend to prove that the sandstones of the 

 Connecticut were produced by a deposition of 

 ancient alluvium from the upper section of the 

 river, and thai the fresh waters mingled with 

 those of the sea, at least as far up as Mount Hoi 

 yoke, and that the deposit took place anterior 

 even to the eruption of that mountain, since the 

 trap rocks of which it is composed were protru- 

 ded through the sandstone, and now rest upon 

 its surliice, where they spread out in a molten 

 state, and now overlap the sandstone. 



It would prove highly intc resting, did our lim- 

 its permit, to carry this S( cliuji tlinmylinut tlie 

 whole valley of the Coinu'ctirut ; but this will 

 not be expected in the priscut K(,'])i)rl, which 

 will he limited to the State of New Hampshire 

 and its immediate borders. 



ARGILLACEOUS AND METAPHORIC SLATES. 



Our great longitudinal section begins at the 

 Connecticut River, at the south-western rornerof 

 the State, at an elevation of 462 feet above the sea- 

 level, departing from the plains of Northfield and 

 Bernardstown, which are underlaid by the red 

 conglomerates and sandstones before described. 



We shall examine next the argillaceeus and 

 metaphoric slates on which the sandstone rests. 

 The argillaceous slates, as mentioned in a for- 

 mer section of this Report, consist of clayey par- 

 ticles, which were originally deposited by water, 

 and were subsequently indurated by the heat of 

 rocks thrown up in an ignited state beneath them. 

 Where the action of the primary rocks was mod- 

 erated by tlie-thickness or remoteness of the stra- 

 ta of setlimentary rocks, the effect upon them ap- 

 pears to have been simply to jnoduce induration ; 

 but where there was an immediate contact, or 

 close contiguity, the slates underwent consider- 

 able changes in structure and composition, or 

 are metaphoric. 



In the towns of Leyden,Beruardstown and Guil- 

 ford may be observed some very interesting pe- 

 culiarities in the disturbance of the argillaceous 

 slates, such as contortions of the strata, shewing 

 that they were once plastic and sofl, crossing and 

 overlapping of strata, effected by lateral thrusts, 

 and the gradual passage or change of argillace- 

 ous into micaceous slate. 



The Gorge or Leydeii Glen is fiequently visit- 

 ed for the sake of its picturesque beauty, and the 

 refreshing coolness of the atmosphere, which 

 renders it a favorite resort for travellcis dining 

 the heat of midsiunmer. The cm-Jous \vill also 



enjoy additional pleasure if they are led to con- 

 template the singular Geological features which 

 this locality presents. It is evident that the slates 

 have been powerfully acted upon by the protru- 

 sion of rocks beneath tlicm, liie strata being cur- 

 ed and bent in various directiniis, while the ar- 

 gillaceous slate exhibits a passage into the mica- 

 ceous slate. Veins of quaiiz are also seen run- 

 ning through the strata, filling fissures originally 

 produced by rupture of its mass. 



In the town of Guilford several deposits of ar- 

 gillaceous slate have been extensively quarried, 

 so that the situation and structure of the strata 

 are exposed to view. One of the most remark- 

 able localities in this town s the slate ledge 

 owned by Mr. Bruce. 



Tlie strata at this quarry are very remarkably 

 situated, and to persons viewing the ledge iu 

 front, the slates ajipear as if they had been bro- 

 ken by a crushing force from above. On more 



inute examination, it may be seen that such 



as not the case, but, this apparent disorderly 

 situation was produced by a crossing and over- 

 lapping of strata, forced out from their original po- 

 sition by a lateral thrust, which may have been 

 effected by the elevation of the neighboring and 

 sidijacent "primai-y unstratified rocks. 



'ibis locality also exhibits decisive proof of 

 the fact formerly mentioned, namely, that the 

 slate strata were sufliciently soft at the epoch of 

 this disturbance to have suffered considerable 

 flexure without breaking ; and we can discover, 

 at the points where flexure and fracture were ef- 

 fected, the degree of flexibility which the slate 

 possessed. 



The following diagram exhibits the manner in 

 which the uppei stnta «ut foiced o\ei those 

 now below, ^o i^ to o\eihp nnd ciine the slates 



Section of Bruce's Slate Quarry, Guilford. 



On the face of the quarry the strata' may be 

 seen crossing each other nearly at right angles, 

 and t)(iey are broken at their points of contact. 



This quarry is wrought to considerable extent 

 for roofing slates, which aie solid and durable, 

 but are not so smooth as those from Wales, or 

 from the quarries in Maine. They are used for 

 covering roofs of houses in Brattleboro', and car- 

 goes are sent down the Connecticut River in 

 boats. 



On the Western side of the Connecticut riv- 

 er, the argillaceous slate rocks predominate, for- 

 ming the sub-strata thoughoul extensive districts 

 iu Vermont, and include many valuable beds of 

 limestone. The same strata extend across the 

 river into New-Hampshire, and overlap the more 

 ancient ])rimary formations of Winchester, Hins- 

 dale, Chesterfield, Walpole, Cbarlestown, Unity, 

 and Claremont, exhibiting those remarkable and 

 interesting metamorphoses in structure and com- 

 position, which have been alluded to in a former 

 section of this Report. It is well known in Eu- 

 rope that the junctions of stratified rocks with 

 the unstratified, are the points most highly char- 

 ged with metaliferous ores ; hence we are led to 

 expect many interesting discoveries in the dis- 

 trirt traversed by this sectional line. 



Leaving the sandstone rocks of Northfield, and 

 proceeding northwardly, we pass over Lonjf Mt., 



