116 



THE FARMER'S MONTHLY VISITOR. 



noticed hereafter. Talcose Slate is distinguished 

 by its color, softness, and unctuous feel when it is 

 rubbed by the fingers. It is a valuable rock, since 

 it ftjrnishes an infusible material for the con- 

 struction of furnaces and lime-kilns, and when 

 compact and soft, it is largely employed in the arts 

 under the name of Soapstone (sometimes called 

 in New Hampshire, Freestone.) This rock exists 

 abundantly in the State, and is wrought to some 

 extent. 



Included in Talcose Slate occur several valua- 

 ble ores, such as Iron, Copper, Gold and Silver. 

 The latter metals have not yet been found in 

 New Hampshire, but at Clareniont a variety of 

 Pyrites is found disseminated in it which exact- 

 ly resembles the Auriferous Pyrites of Siberia and 

 of the Southern .States. yMthough I do not con- 

 sider the precious metals so worthy of attention 

 as those which are more commonly serviceable, 

 yet I would direct the attention of those who are 

 desirous of discovering these metals in the State 

 to an attentive examination of this rock. It must, 

 however, be remembered, that gold is rarely 

 found in particles visibleto the naked eye, excep- 

 ting in the decomposed and washed ore. 



ARGILLACEOCS SLATE. 



Tliis rock is composed of the finest particles 

 of antecedent rocks which were deposited slow- 

 ly by tranquil water. The influence of pressure 

 and heat appears to have consolidated the clay 

 thus formed into a solid rock, which has a strat 

 ified structure, owing to the manner of its de|i- 

 osition. 



By subterranean power the slates have been 

 elevated, so that their strata now form a bold an- 

 gle with the horizon. The upheaving rock in 

 New Hampshire was evidently the granite, which 

 not only uplifted the strata, but also broke through 

 it, and spread upon its surface. On Piquacket 

 Mountain, in Bartlett, the traveller may observe 

 a striking instance of such a disruption ; for there 

 the broken slate forms a confused mixture with 

 the granite that burst through its strata. 



Argillaceous Slates are of different ages, and 

 were formed under dift'eient circumstances. 

 Those to which I now refer are deposited im- 

 mediately upon the prinwry rocks, and belong to 

 the oldest transition class. Their lower strata do 

 not contain any organic relics, but higher up -we 

 find a few remains of marine animals, and plant« 

 of the simplest structure. 



Slate rocks are valuable for use in the arts 

 when they have a unilbrin cleavage, and^are even 

 and sound. The more compact varieties are 

 used for grave-stones, while those which are fis- 

 sile are valuable for covering the roofs of hoo- 



REl'ORTS ON TUE SECTIONAL PROKILES OF THE 

 ROCKS. 



In order to ascertain the extent and limits of 

 the priucipal rocks, beds, and veins, and their re- 

 lative situation, as also the elevations and depres- 

 sions of the surface of the countrv, a series of 

 sectional lines were measured an(^ explored in 

 directions alternately transverse and parallel to the 

 general direction of strata. 



The first of these great sections extends from 

 the southeastern extremity of the State, at Ports- 

 mouth, to Claremont on the Connecticut river, 

 passing through the State in a northwesterly d 

 rection, and crossing all the N. E and S. W. stra- 

 ta, nearly at right angles. 



The second great "section was laid out on the 

 eastern side of the Connecticut river, and runs 

 parallel with the general course of that river, ex- 

 tending from Northfield in Massachusetts, to Ha- 

 verhill in New Hampshire, and pursues a direc- 

 tion a few degrees eastward of a meridional line. 

 A third section extends from Concord to 

 Wakefield, and the fourth from Wakefield to Ha- 

 verhill. 



By inspecting the State map, it will be seen 

 that these lines form a series of zig-zags on a 

 large scale, and the profile of their Geological 

 features represents the actual structure of the 

 rocks and mountains, the inclination of the stra- 

 ta, centres of elevation, and the nature of the in- 

 truded rocks which effected the upheaving of 

 the stratified rocks which repose on them. 



Those who have not attended to the subject, 

 may not fully understand the nature of these sec- 

 tions, and I would therefore observe, that they 

 represent the structure of the country as it would 

 appear it a straight line was drawn from one of 

 the points mentioned to the other, and then a 



perpendicular cut was made through the rocks, 

 along the whole length of the line, quite down 

 to the level of the sea. It is customary, in order 

 to avoid a very long profile, to draw jilans 

 such a manner that the scale of the length is 

 considerably less than that of the height, bi 

 have endeavored to keep the proportions within 

 proper limits, so that the sectional profiles have 

 a more natural appearance than those which are 

 commonly drawn for such purposes. In limited 

 districts, it is easy to draw plans in such a man 

 ner that the scale of length and of height are tht 

 same,but one running across a great State cannot 

 be represented in that manner without elongating 

 the profile so as to render it cumbersome and un- 

 manageable. 



I have seen some beautiful models of the stnic- 

 ture of mountainous regions in Switzerland and 

 in Pennsylvania, whicli were constructed of plas- 

 ter, stucco, or paper mash mixed with gyiisum. 

 Such models may be made to represent tlie Geo- 

 logical and topographical structure of New Manip- 

 shire, when we have measured the elevations of 

 all the mountains and the depth of the valleys, 

 but the work would prove very expensive, 

 would require more time than is allowed for the 

 Geological Survey of the State. I hope, howev 

 er, that some artist will hereafter construct such 

 models of the White mountain ranges, and then 

 is but little doubt that travellers would most glad 

 ly purchase copies of them as Souvenirs of tlia; 

 pictercsque region. 



SECTIO.N- FIRST, FROM PORTSMOUTH THROtJGH 

 CONCORD TO CLAREMONT. 



Having e.\amincd the -extremities and some 

 few points on this line, the survey of a sectional 

 Geological profile was confided to my assistants, 

 who performed the work in a satisfactory man- 

 ner, and their Report is herewith presented in 

 connexion with the remarks wliich I have to of- 

 fer on the outlines of the Geology of Portsmouth 

 and its vicinity. 



We shall first present a few remarks on the 

 Geelogy of the Isles of Shoals, which are situa- 

 ted near the southeastern extremity of our first 

 section. 



ISLES OF SHOALS. 



Tiirough the politeness of Captahi Currier of 

 Portsmouth, we were enabled to visit the Isles of 

 Shoals, in the U. S. Revenue Cutter. These Isl- 

 ands form the extreme outposts ot the State, and 

 are situated about 10 miles S. S. E. from Ports- 

 mouth harlior, in the open sea. Having frequent- 

 ly seen these Islands at a distance on former oc- 

 casion.s, I did not expect Jo find much that would 

 be interesting in their Geology, but since they 

 form the extreme jioint of our first section, it be- 

 came necessary to examine them. There are 

 seven Islands and a lew rocks, whicli have re- 

 ceived the name of the Isles of Shoals. They 

 are all composed of ledges of i-ock, and but few 

 of them possess any soil suitable for agriculture. 



The inhabitants i-ely mostly on the treasures 

 of ihe deep for sustenance, are expert fishermen 

 and excellent mariners. Singular as it may ap- 

 pear, it is stated that on these remote and lonely 

 islands, the first settlers of New Hampshire fixed 

 their abode, and dwelt there many years before 

 settlements were effected on the main land. It is 

 supposed that an isolated situation was chosen in 

 order to avoid the hostile incursions of th 



S. .50 deg. W. direction. There is but little soi' 

 on the surffice of the rocks, serving in a few 

 places for kitchen gardens for the cultivation of 

 potatoes, and a few ordinary vegetables. The 

 inhabitants depend on the agricultural produce of 

 the main laud, and exchange for them the pro- 

 ducts of the sea. Hog Island is composed most- 

 ly of mica .slate rocks, and has a thin covering of 

 soil, but is not cultivated to any extent. 



leu ot" (losport un St.ir Island olF Portsmouth Harbor. 

 Duck Island is conqiosed of Granite and Gneiss 



)cks. The only soil existent on its surface fills 

 the irregular depressions of the rocks, and sup- 

 ports a few of the hardy wild gi-asses, bushes, 

 and a few maritime flowering plants which are 

 common on our eastern coast. The Island prob- 

 ly takes its name from the abundance of sea 

 fowl which frequent its shores, and deposit their 

 eggs on tlic rocks or among the grass. 



Owing to tlie heavy surf which dashed upon 

 the shores of the Islands, we were only able to 

 effect landings in a few places ; the others, being 

 seen from the deck of the cutter as we ran close 

 by them, appeared to consist exclusively of coarse 

 granite, broken occasionally into huge cuboidal 

 blocks, and possessing but little Geological in- 

 terest. 



The following are the names of the Islands 



1st. Star Island, on which is situated the vil- 

 lage of Gosport. 



9d. White Island, on which there is a light 

 house. 



3d. Hog Island, which belongs lo the State of 

 Maine, has two or three dwelling houses upon it. 



4th. The Londoner is a smrdl rocky Island 

 having a light liou.se upon it. 



5th. Cedar Island. 



6th. Smutty Nose. 



7th. Duck Island. 



Gosport is a small village, inhabited chiefly by 

 fishermen, whose numerous boats moored near 

 the town, presented the appearance of a grove of 

 slender masts. The town has one small meet- 

 ing house. 



The Island is composed of a coarse variety of 

 granite, having large crystals of white felspar, 

 grey quartz, and but little mica. Intercalated 

 beds of mica slate also occur in the granite. 

 Through the middle of the Island runs a large 

 dyke of greenstone trap rock, in a N. .50 deg. E., 



Near the light-house at Fort Constitution, on 

 Rease's Island, several largj; ami well characteri- 

 zed dykes of Greenstone Trap are seen cutting 

 through the slate rocks, and they occur at numer- 

 ous other places near the mouili of tlie river. 



