HE FARMER'S MONTHLY VISITOR. 



185 



gypsum, horiiblend, lionistoue, liraeeloiie, mica, 

 quartz and talc. 



As no fossil remains have been found imbed- 

 ded in the primary rocks it is universal!)' conce- 

 ded that the period of their formation must have 

 been anterior to the existence of animal or ve- 

 getable life. And as regular gradations of min- 

 eral character extend fiom the modern lavas, 

 trachytes and ])orphyrics, through trap and ba- 

 salt to infinite varieties of serpentine greenstone, 

 sienite and finally lo granite, we cannot but relcr 

 them all to a common igneous origin. 



A/ourth result of the same phenomena, was the 

 formation of metalic veins. As the mean density 

 of the whole earth is about double tliat of its ox- 

 idized crust, its composition taken as a body is 

 supposed to be metallic. Indeed but little doubt 

 remains since the im]iortant discovery by Sir H. 

 Davy of the metallic nature of our surface soils, 

 alumina, calcia and magnesia, that all the differ- 

 ent materials which enter into the composition of 

 the solid parts of our globe have metallic bases 

 although a few ametalics as boron, carbon, fluo- 

 rine, iodine, phosphorus, seleifumi, silicon and 

 sulpher, have as yet resisted the analysis of the 

 chemist to olrtain a claim to that character. 



As before suggt!Stcd the denser metals in a 

 state of fusion would tend towards the centre 

 while the lighter would become oxidized upon 

 the surface of the earth and it would require 

 some extra effort of subterranean dynamics to 

 tlu'ow up the denser metals and form veins and 

 detached masses of these metals in the fractures 

 and chasms of the primitive rocks. But what- 

 ever might have been the nature of the forces 

 which caused their elevation we find them most- 

 ly, to be sure, in the rents and fissures of tlie prim- 

 itive formation though frequently in such of the 

 transition and secondary and even tertiary strata 

 as are superincumbent upon, and lying immediate- 

 ly in contact with the ]irimary. These fissures 

 are more or less filled with various forms of me- 

 talliferous and earthy minerals, deposited in suc- 

 cessive and oflen corresponding layers on each 

 side of the vein. Occasionally, a metal is found 

 disseminated throughout the substance of a rock, 

 as tin is sometimes disseminated in granite, and 

 copper in the slate of the Mansfield H;'.rtz. But 

 these cases are rare. In general the metallic 

 veins are distinctly fonnod, varying much in their 

 width and unequal in their depth; sometimes 

 running out after a short distance, and .:it others 

 descending to unknown depths below tlie sur- 

 face ; but still in a gancuo ditlercnt (ionithe min- 

 eral product siUTOunding it and exhibiting a dis- 

 tinct formation. 



The most numerous and valuable of the metallic 1 

 veins of Cornwall in England, and in many other 

 mineral districts are found n.'ar the junction of 

 the granite with the slate. These vary in width 

 from less than one inch to more than thirty feet, 

 but the prevailing thickness of the veins both of 

 copper and of tin in that county is from one to 

 three feet. And it hnsbeen fbmid tlmt in these 

 narrower veins the ore is less intermixed with 

 other substance s and consequently wrought 

 to belter advantage. But the [jrimary rocks are 

 not the oidy depository of metalllic veins. 

 Mines of haematite and spathose iron ore found 

 in the Eastern Pyrenees in limestone of three 

 agt 8 referable severally to the transition series, 

 to the lias and the chalk, situated however where 

 the limestone is in near contact with the gran- 

 ite, and the consequcncG has f.een to crystalizc 

 the limestone wherever the two minerals have 

 come together. Also in tlie Cordilleras of Chili 

 at an elevation of fourteen thousand feet the 

 granite has evidently been fluid so late as the de- 

 jiosition of the tertiary strata, sections of which 

 strata have not only been rendered crystaline 

 but are traversed with dikes froni the granitic 

 mass beneath, inclined at high angles and form- 

 ing regular and complicated anticlinal lines. 

 Those dikes with the accompanying lava are fill- 

 ed with very nmnerous true metallic veins of 

 iron, copper, arsenic, silver and gold, all of which 

 can be traced to the granite mass before mention- 

 ed. 



The gold mines of North Carolina are found 

 in talcose slate, and the Pliitinum mines of the 

 Ural are fbimd not only in talcose slate, but in 

 volcanic porphyry, m clianged limestone near in- 

 trusive granite and green sand, the detritus o! 

 primary rocks. 



Several hypothe'ieB have been advanced to ex- 



l)lain the rationale of the Ibrmation of metallic 

 veins. Werner siqiposed that they were filled 

 from aljove by the substances suspended in a 

 state of aqueous solution. Hutton believes that 

 their contents were injected from below in a state 

 of igneous fusion. Mr. Patterson refers the 

 process lo sublimation from subjacent masses of 

 intensely heated mineral matter; while Mr. Fox 

 attributes it to slow segregation or infiltration mod- 

 ified and controled by electro chemical agency. 

 But in whatever way formed, one thing is cer- 

 tain, that the total quantity of all the metals 

 known to exist near the surlace of the earth with 

 the exception of iron and perhaps of lead, is com- 

 paratively small ; — their value to man being of 

 the utmost consequence, they are so placed by a 

 wise and beneficent Providence as to be out of 

 the reach of immediate and improvident exhaus- 

 tion ; exercisins all om- ingenuity first to find 

 theni, and then to overcome the difficulties by 

 which their attainment is surrounded. 



A fijVi result was the conmiencernent of ani- 

 mal and vegetable life. Hitherto the temperatin-e 

 had been too elevated and the convulsions too fre- 

 quent lor the conuneiicement or temporary safe- 

 ty of animal or vegetable existence, even in its 

 lowest and most simply organized forms. But a 

 new era had commenced. A state of conq)ara- 

 tive repose from chaotic convulsions and a re- 

 duction of temiieratiu-e comj)atible with organ- 

 ized beings was obtained. The crust of the 

 earth had assumed a depth and firmness indica- 

 ting at least for a time a comparative state of re- 

 [lose. 



V'egetable and animal existence were proba- 

 bly nearly simultaneous in their origin. The 

 first of tliese commencing on the sands of the 

 narrow istlimuses which surrounded those isola- 

 ted sea.s, were in the form of the tropical ferns, 

 and assisted by a high temperature and profuse 

 evaperation, soon attained a size and elevation 

 far exceeding their congeners of the present 

 age. Happily the existence as well as the size 

 and species of these' gigantic plants rests not upon 

 the conjectures of speculative theorists, but, 

 treasured up in the subterranean storehouses of 

 the I'arboniferors strata, they still exist as monu- 

 mental records of the past. In the coal fields 

 we find jilants resembling in their texture and 

 striicttu'e the club moss, the arborescent fern, 

 the horsetail and scoiu'ing rush of the present 

 times attaining tlie size of our largest forest 

 trees. The history of fossil plants goes to show 

 that of the plants of the transition strata more 

 than one Inmdrcd and twenty of the known sjie- 

 cics were ferns forming almost one half of the 

 entire flora of that period. The others were in- 

 termediate between the ferns the mosses and the 

 pines, a few of the last being even then in exis- 

 tence. Of the plants of the secondary strata 

 about one third were ferns ; the remainder were 

 mostly cycadeaj and couil'erre with a few of the 

 lilly tribe. The vegetation of the tertiaries ap- 

 |)roximated clearly to that of the |)rescnt period. 

 Thus among living plants the nearest relation to 

 the earliest forms are the seaweeds, ferns, mosses, 

 cycas and jiines. The fiimily that has most uni- 

 versally pervaded every str.ge of vegetation is 

 the conifera;, increasing in the number and varie- 

 ty of its genera and species at each successive 

 change in the climate and condition of the sur- 

 face of the earth. This family fonim ut thu 

 present time about one three hundredth part 

 of existing vegetables. Another family which 

 has pervaded all the series of formations, though 

 in small proportion, are thejialms. 'i'hc iHuiil.cr 

 of fossil plants already described is about five 

 hundred, nearly three hundred of which are 

 from the transition series, and almost entirely 

 from the coal formation. About ono hiuidred 

 arc from strata of the secondary series and some- 

 what more tlian tliat number from the tertia- 

 ries. As the known species of living plants are 

 more than fifty thousand it proves conclusively 

 that the jiresent admixture of soils and reduction 

 of temi)erature is far more congenial to the ex- 

 tent and variety of vegetation than any fi^rmer 

 period ol' the history of the earth. As the first 

 outlines of vegetation commenced on the isth- 

 muses, so the first germs of animal being ' eiian 

 ia the deeper of those isolated seas enclosed by 

 tliem, and were in the commencement exclusive- 

 ly marine. The Ibssil remains of the first series 

 are those of zoopliites, crustaceans and mollusks. 

 In the second of these belonged the family of the 



trilobites, remarkable for their early extinction, 

 none being found later than in the carbonili'rou.s 

 strata of the transition series; as also tor their 

 almost miiversal diffusion, being Ibuiid in great 

 numbers in almost evei7 section of the iilobe. 

 To these succeeded at an early period the fiuuily 

 of fishes, many of them of "a large size and 

 destructive character, amongst which the sharks 

 and megalichthys or lizard fislies were predom- 

 iirant. These were followed by the samians or 

 lizards and indeed the peculiar f(?atures in the 

 population of the whole series of secondary stra- 

 ta was the prevalence of numeious and gigantic 

 forms of saurian reptiles. Many of these 'were 

 exclusively marine; others ani|)hibious ; others 

 terrestrial, ranging the savannahs and jungles 

 clothed with a tropical vegetation ; while othei's 

 even tenanted the air under the dragon form of 

 flying lizards or pterodactyles. Of the marine 

 saurians the most remarkable were the ichthyos- 

 aurus and plesiosaurus fiom their size and des- 

 tructive powers reigning the tyrants of the ocean, 

 some of their fossil remainsj exceeding thirty 

 feet in length. And just at the time when their 

 existence among the timnlies of the ocean ceased, 

 which was dm-ing the deposition of the chalk a 

 new genus, the mosasaurus, appeared desliried 

 for a while to supply their ofiice ami place, and 

 at length jield both to the cetacia of the tertia- 

 ry periods. Of the amphibious reptiles together 

 with five or six species of crocodiles appeared 

 the inegalosaurus an enormous lizard fiom forty 

 to fifty feet in length partaking of the structine of 

 the crocodile and the monitor. The hylaeosau- 

 rus or lizird of the weald was intermediate in 

 size between the lust and the crocodile, beino- 

 about twenty five feet in length. Of the terres^ 

 trial saurians the iguanodon found also in the 

 Wealden fresh water formation, jiresented a 

 length of seventy feet with a liody fourteen and 

 a half feet in circumference. And to finish the 

 strange picture of these monstrous inhabitants of 

 the land and waters of our inliint world ^ve find 

 the filing saurians or pterodactyli presenting a 

 series of anomalies in their structiu-e which the 

 genius alone of a Cuvier could reconcile. 



Altliough a continued series of revolutions had 

 materially changed the face of the ea.rtli since 

 the commencement even of organic life; still the 

 condition of the globe at the period of wliicli we 

 are speaking seems not sufficiently advanced in 

 the work of renovation to admit of its general 

 occiq)ancy by warmblooded terrestrial mammal- 

 ia. The first evidence we find of their existence 

 is in the forest marble of the oolitic strata, situa- 

 ted in Ihe ascending series about midway be- 

 tween the transition series and the to-liary" for- 

 mations. This was the fossil skeleton of the 

 didelphis bucklandi, an extinct s[)ecics of the 

 family of o))ossums. That animal, the first spe- 

 cies perhaps of created mammalia, was extinct 

 in the eastern continent long before the com- 

 mencement of the historic jieriod ; hut its con- 

 geners are still found in the opossum of our ov,n 

 country and the kangaroo of New Ilollsnd. 



But Ibssil remains of quadrupeds ai-e extreme- 

 ly rare until we arrive at the tertiary deposits, 

 where they are found in abitiidance ; and hero as 

 if nature to make amends for the tardines;s of 

 their api)carance, put forth al! her poweis, in the 

 diversified forms and extraordinary mngnitmlc of 

 lier naw creation. In the first great fresh water 

 formation of the eocene tertiary fifty exlii.ct sne- 

 eies of mammalia were discovered byCuvi,?r. 

 The largest of these was the palpcotlieriuni, an 

 animal it appears which was the size of the 

 largest rhinoceros and intermediate in ibrm be- 

 tween the rhinoceros, the horse, and tlie tairir. 

 Eleven or twelve species have already been dis- 

 covered, some smaller than oihersj biit ail of 

 extraordinary strength and magnitude. ^ 



Another animal of extraordiiiary size and re- 

 feralde to this ]ieriod was the sivatherimri ot In- 

 dia, an animal intermediate bel ween the rliinoce- 

 ros and tajiir, but larger even than the first named 

 animal and Ibmid in the Sivalic or Sidi llimaljiyan 

 range of hills between the .Jumna and the Gan- 

 ges. 



In the basin of Eppleshiem rem'hiiis of the 

 following ainniids referable to the miocenc tertia- 

 ries have been found, viz : two species of dii:o- 

 iheriimi or gigantic tapir — tv. o species of the ta- 

 pir much 1,-irgerthan the living animal — two spe- 

 cies of the chalicotherium allied also to the tapir 

 — two of the rhinoceros — one species of tefr.n- 



