THE FARMER'S MONTHLY VISITOR. 



CONDUCTED BY ISAAC HILL. 



" TTiosc who labor in the earth are the chosen people of God, whose breasts he has made his peculiar depositefor tubstaniial and gtmiine virtue." Jeffersok. 



VOLUME III. 



CONCORD, N. H. AUG. 31, 1841. 



NUMBER 8. 



THE FARSIER'S MONTHLY VISITOR. 



A MONTHI.y NKWSPAPER, IS PUBLISHED By 



JOHN M. HILL, 



Hill's Brick Block, Concord, A". H. 



GENERAflGENTS, 



B. COOKE. Keene, N. H. 



TH. R. HAMPTON, Washington City, D. C. 



JOHN MARSH. Washington St. Boston. 



CHARLES WARREN, Brintey Row, Worcester. Mass. 



A. H. STILLWELL, No. 1, Market Square, Proc. R.J. 



'IKORGE W. TOVVLE, Portsmouth, N. H. 



L. W. HALL & Co. Springfield, Mass. 



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An Index and 



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First Annual 



State of New Hampshire 



Bv Charles T. Jackson, Stale Geologist. 



SUPER-POSITION OF ROCKS. 



The locks which form the crust of tlie earth 

 have been examined by Geologists, who have 

 classified them according to their order of super- 

 position and origin, or by tlieir mineral and fos- 

 sil contents. Occasionally it has been thought 

 proper to^ designate certain groups of rocks by 

 names referring to localities, where it was sup- 

 posed their most chai-acteristic features were 

 presented. 



Some rocks have evidently been in a melted 

 state, and were erupted from the interior of the 

 globe : others were deposited by water, which 

 held the particles of pre-existent rocks in sus- 

 pension, or more rarely in solution. Some of 

 the rocks which were originally deposited by 

 water, subsequently underwent changes in struc- 

 ture and composition, by the influence of .heat 

 proceeding from the erupted rocks. 



Hence we have rocks produced by fire which 

 are designated as of igneous origin, Plutonic 

 or erupted rocks, while those which were depos- 

 ited by water are styled rocks of aqueous or Nep- 

 tunian origin, and those deposited by water, and 

 subsequently changed in structure by fire, are 

 named metanmrphic rocks. 



Another method has also been proposed, 

 namefy, to divide rocks into two great classes, 

 without reference to any theory of iheir origin ; 

 and those two classes are the umtralified and the 

 stratified rooks. The unstratified rocks generally 

 are those of igneous origin, while those which 

 are stratified were deposited by water. 



At or near their junction, we find the altered 

 or metaniorphic rocks. 



This method is a very good one for the gen- 

 eral groups, but more details are required for the 

 full elucidation of the characters of the subordi- 

 nate divisions. 



If we consider the rock called Gneiss as a point 

 of departure, we shall find above it all the strat- 

 ified rocks arranged in their order of deposition; 

 and below it we have the unstratified rocks, and 

 the matter which produced them. 



By upheaving force the matters forming the 

 unstratified rocks burst open the gneiss and ma- 

 ny of the strata resting upon it, and the molten 

 rock pushed up/rom below, filled the chasms, 

 or flowed through them and spread on their sur- 

 face. It is easy, then, by ascertaining what stra- 

 ta were burst ojieii by veins or dykes, to deter- 



mine with some degree of accuracy their com- 

 parative age. 



ROCK formations. 



The term formation is applied in Geology to 

 designate groups of rocks, formed under certain 

 conditions of the globe, or their relative ages. 

 Thus we have the primary formation or rocks 

 that were first produced. They are regarded as 

 the oldest in the series, and were produced an- 

 terior to the e.xistence of animals or plants, no 

 traces of organized beings having ever been dis- 

 covered in them. It is supposed that the earth 

 at the epoch of their formation was not in a suit- 

 able condition to allow of the e.xistence of living 

 beings on its surface. 



The rocks belonging to this group are gener- 

 ally of a crystalline character, and bear the im- 

 press of igneous.action. Resting upon tlie prima- 

 ry group, is the next class of rocks, originally 

 named by Lehman, the secondary formation, but 

 subsequently Werner proposed to designate the 

 lower series by the name of transition, indicating 

 that they formed a gradation from the primary to 

 the secondary, or that the world was undergoing 

 a transition from an uninhabilable to a habitabi 

 state, for in these rocks we find the first remains 

 of organized beings. There has been much dis- 

 cussion as to the propriety of this term, and 

 ny Geologists prefer to omit it and to return to 

 the numerical arrangement proposed by Lebm&n, 

 calling the transition rocks the older secondary. 

 This method has the advantage of keeping the 

 numerical names of the upper formations, as 

 they now are, allowing the general introduction 

 of such an arrangement is to he adopted. 



The older secondary or transition rocks were 

 deposited by water, and weie originally in the 

 condition of fine' mud, sand and gravel at the 

 bottom of the sea. This must be evident from 

 the fact that the perfect forms of marine shells 

 and crustaceous animals are preserved in its 

 mass. The fossils called Trilobites are charac- 

 teristic of this formation. 



This group of rocks extends as high as the coal 

 measures, or the rocks which contain coal. 



We then reach the ujiper secondary group, 

 which extends to the top of the chalk deposits. 

 The secondary rocks are filled with an infinity of 

 organic remains, both of animals and vegetables. 

 In this formation our vast deposits of bituminous 

 coals and anthracites occur, overlaid and under- 

 laid by shales containing impressions and casts 

 of numerous plants, analogous to the genera 

 which grow only within the tropics, but whose 

 species, like all those emliedded in this and the 

 okler rocks are extinct. Over the eoal forma- 

 tion, we find the new red sandstone, lias lime- 

 stone, oolite and wealden rocks and chalk. At 

 this point the secondary formation ceases, and 

 nother class is formed, which consist of clay, 

 calcareous sand and marl, the strata of which 

 are filled with myriads of marine and fi-esh wa- 

 ter shells, and with the remains of plants and of 

 animals of the higher orders. 



This deposit is called the tertiary formation. 

 The tertiary rests upon any kind of rock that 

 happened to be uppermost at the epoch of its 

 deposition. 



The primary formation appears to compose 

 the principal portion of the State, so far as the 

 rocks of New-Hampshire have been examined. 

 In some limited districts, we have found altered 

 argillaceous slates belonging to the Cambrian 

 System of Prof Sedgwick. 



Intruded dykes of greenstone trap also a- 

 bound. 



A few limited patches of tertiary, a deposit of 

 clay containing marine shells, also occur in the 

 vicinity of Portsmouth. 



The primary rocks frequently contain veins 

 and beds of limestones and metalliferous ore.s. 

 The stratified rocks of this class are always 

 highly inclined to the horizon, the angle of the 

 dip being from 40 to 80 degrees. 



Owing to this uptilted state of the strata, it is 

 easy to inspect the order of superposition, and 

 to discover the different veins and lieds which are 

 included in the rock. This position also affords 

 admirable facilities for measuring the thickness 

 of the strata. 



GRANITE. 



Granite is the lowest rock which has been 

 reached by the deepest mines, and it also forms 

 the peaks of many lofty mountains. 



It is the foundation rock on which all the more 

 recent formations rest, and many of the superin- 

 cumbent strata are made up of its fragments. 

 It is a rock of igneous origin, and has no strat- 

 ified structure. 



When granite is found cutting through other 

 rocks, the action of intense heat may often be 

 observed at the junction and to a considerable 

 distance b(;yond the points of contact 



When it intrudes through slate, that rock is 

 found to be hard and flinty at or near the junc- 

 tion, and the strata marks are generally effaced. 



If the eruption took place through compact or 

 shell limestone, the carbonate of lime is obser- 

 ved to become crystalline or white in the vicinity 

 of the granite. By a series of such observations, 

 the most distinguished Geologists have satisfied 

 themselves that granite was thrown up in an in- 

 tensely heated or molten state. By slow cooling 

 of a semi-fluid mass of melted rock, crystals are 

 formed in its midst, and in cases wlxire the mass 

 of matter was of great bulk, the cooling took 

 place so slowly as to allow very large and perfect 

 crystals to form. So in granite, we find the rock 

 to be made up entirely of crystals, nierely^held to- 

 gether by contact and interlacement. 



SiENiTE differs from granite only by the sub- 

 stitution of hornblende in the place of mica, but 

 it sometimes contains more felspar. 



MINERALS ENTERING INTO THE COMPOSITION OP 

 GRANITE ROCKS. 



Three difterent minerals enter into the com- 

 position of regular granite. They are quartz, 

 felspar, and mica. In addhion, there are fre- 

 quently a number of other species, which are 

 called accidental or associated minerals. Some- 

 times one of the essential ingredients of the rock 

 may be absent, and in such cases it is generally 

 replaced by some other. Hence there are a 

 great number of varieties of granite, such as I 

 shall have occasion to describe hereafler. 



Quartz is a glassy looking substance, either 

 transpaient and colorless, or shaded by various 

 tints, from the presence of metallic oxides. 



When jiure, it consists entirely of silex. It is 

 then altogether infusible by the most intense 

 heat of the fiirnace, or by the common blow-pipe 

 flame. 



It is as hard as common flint, and scratches 

 glass readily. When crystallized, it generally is 

 found in the form of a six sided prism, termina- 

 ted hjy six sided pyramids at each end of the 

 prisni, if the crystal formed in a space where the 

 extremities were free from the rock ; but more 

 frequently one end of the crystal is found im- 

 planted firmly in the rock where it crystalized, 

 and t^en only the free extremity is perfect. 



The primary and simplest form of quartz crys- 

 tal is rarely found. It is a rhomboid having an- 

 gles of 94deg. 15m. and 85deg. 45m. Some- 

 times we can cleave or split a secondary crystal 

 so as to obtain this form. 



The specific gravity of quartz is 2.645, water 

 being considered as unity. 



When struck against steel, quartz tears off 

 small fragments of the metal, which take fire in 

 the air, owing to the heat produced by concus- 

 sion, and the rapid oxidation of the iron or steel 

 by the oxigen of the atmosphere. It will there- 

 fore answer for striking fire like flint. 



When two pieces of quartz are struck togeth- 

 er in the dark, a faint flash of light is seen, which 

 is not fire, but is an electric phenomenon called 

 phosphorescence. The rock is found, upon fric- 



