174 



♦ KNOWLEDGE ♦ 



[ArniT, 1. 1886. 



Seas as remnants of the shallow waters that had linked 

 together the Baltic and the Persian Gulf, the Arctic and 

 the Indian Oceans. 



Except in the gradual extinction of the larger species, the 

 hippopotamus alone surviving to this day, the mammals 

 varied little from those of the INIiocene, the most remarkable 

 anions the carnivora being the fierce sabre-toothed felines. 

 But fauna and flora alike witness to a cooling climate. The 

 life-destroying agencies are at work ; the cold fingers of the 

 ice-giant are being spread over the northern hemisphere 

 to the 50th parallel of latitude, dinting and rounding 

 its surface, and leaving to this day the ti-aces of their 

 impress in the snow-fields and glaciers of Scandinavia and 

 Switzerltmd. 



Upon the glacial deposits, or boulder clays, only the most 

 recent of which contain fossils, and tliese poor and scanty, 

 rest the strata of the pi-esent geological epoch, the Qualer- 

 iiarii, or Post- Tertiary, or Pleistocew, as it is variously 

 called. This is subdivided into the Post-Pliocene and tlie 

 Piecent, the former containing the i-emains of many extinct 

 animals, as huge wingless birds and sloth-like mammals ; 

 and the latter the remains of none but existing species. It 

 is to some early, perhaps a milder interglacial, period in the 

 Quaternary epoch in Western Eui'ope that the first appear- 

 ance of man, the latest and highest animal, is to be referred, 

 the evidence of this being more in his works than in him- 

 self, for the scantiest remains of his fragile skeleton have 

 been preserved. The roughly chipped stone tools and 

 weapons with wliich he made shift have been found buried 

 in ancient river gravels with bones of the mammoth or 

 woolly-haired elephant and other arctic animals, as well as 

 with bones of temperate and tropical animals, witnessing to 

 sharp alternations of climate. Stone implements and rude 

 works of art of a somewhat more advanced race, possibly 

 allied to the Eskimo, have also been found associated with 

 remains of sub-arctic animals in limestone caverns. How 

 long before this man appeared on the earth, or whence came 

 the Drift- men and the Cave-men, we cannot say. So far as 

 our present imperfect knowledge of " primitive " man goes, 

 the Pala'olithie or Old Stone Age marks the limits of his 

 place in the life-record. A wide gap of different conditions 

 separates tlie rude savages of that age from the progressive 

 races of the succeeding periods into which pre-historic time 

 is divided — namely, the Neolithic or Newer Stone Age, the 

 Age of Bronze, and, lastly, the Age of Iron, which merges 

 into the brief and modern period embraced by the historian. 



In the foregoing rapid summary of the earth's past 

 zoology and botany much of detail has been left out 

 for cleai'er presentment of the typical features of each 

 e])Och and of the scale of life as an ascending scale. The 

 older the rock the simpler the life-forms. 



The lichen and the seaweed, stemless and leafless, are 

 lower than the club-moss and the tree-fern ; these are lower 

 than the true timber-tree with its complex arrangement of 

 trunk, branches, leaves, flowers, and fruit. The shapeless 

 amoeba is lowest in the scale ; the sponge, rooted plant-like 

 to the rock, is lower than the coral or the starfish ; these, 

 again, than crabs or shell-fish, the most highly organised 

 of wliich are lower than the vertebrates, between the 

 several groups of which the ascents are manifest in fish, 

 I'eptile, bird, and mammal. And among these last there 

 are the lesser and the greater ; the pouch-bearers, bringing 

 forth their .young immature, are less specialized than the 

 placentals, bringing forth their young fully developed ; while 

 here, also, the ascending grades are seen in whales, ungu- 

 lates, carnivoi-a, monkej's, men. 



To all which the fossil-yielding rocks bring their witness. 

 Imperfect as is their record, obscure as in certain cases are 



the causes of modification resulting in the appearance of new 

 types, the evidence as to ascent of life from the simple to the 

 complex, and as to its succession, is overwhelming. There 

 was a time when the earth was devoid of life, and we are 

 doubtless very far from its " protoplast " beginnings in the 

 earliest known organic remains, just as .all species probably 

 came into being long before we have any trace of them. 

 But no evidence as to their real first appearance that may be 

 gathered from pai-ts still unexplored is likely to alter the 

 relative order assigned to the several types as compared with 

 one another. 



Table of the Successive Appear.'Ince of Typicai, 

 liee-foems. 



Epocl). 



Eozoic 

 (Earliesc 

 Lite-forms) 



PliiMART or 



PAL.EOZHIC 



(Age o£ Ferns 

 and Fishes) 



Secoxd.\rt or 



Mesozoic 

 (Age of Pines 

 and Reptiles) 



Teutiart or 

 Cainozoh- 



(Age of Ltftf. 

 forests and 

 Mammals) 



Quaternary 



System. 



Laurentian 

 Cambrian 



Silurian 



Devonian 

 Carboniferous 



Permian 



Triassic 



Jurassic 



Cretaceous 



Eocene 



^riocene and 

 Pliocene 



Eozoon Canadense (?) 

 Sponges; corals; Crustacea;! 



sliell-Ssh 

 Huge Crustacea ; the lowest 



known vertebrates (ganoids 



or armoured ^M) 



Insects ; swarms of ganoids 

 Laud vertebrates (LabjriutUo- 

 donts) 



Immense reptiles ; marsupiaJ 

 mummals 



Immense bird-reptiles ; true 

 birdi" 



Bony-skeletoned fisli ; large am- 

 monites 



Huge plficfii/ul m'linm'ih ; ser 



jients ; uummulites 

 True whales ; JIati-like Apes 



(Glacial Epoch intervening, .and contlnu-] 

 ing intotbe) 

 Post-Pliocene Mammoth and other woolly 



quadrupeds ; Man 

 RecentorHis- Existing species 

 toric I 



Plant. 



Sea-weeds, club- 

 mosses 



Ferns, calamites, 

 cycads 



Conifers, palms 



Trees, shrubs, 

 herbs allied to 

 existing sub- 

 tropical species 



Arctic and tem- 

 perate 

 Existingspecies 



- The discovery of the lowest mammalian forms in earlier strata than those con- 

 taining birds seems opposed to the accepted order of succession, but there is con- 

 siderable uncertainty as to the exact pariod of the first appearance of birds. 



The hi.story of the earth is written by fire and water ; 

 its life-history by water alone. 



The volcitnic and other modes of igneous disturbance 

 that have upheaved, depressed, contorted, and fissured its 

 cooling crust are due to the internal energy manifest in 

 the escape of pent-up heat and in chemical action. The 

 more potent agents of change in the visible crust, however, 

 have not been from within, but from without. As the 

 intern-al enei'gy, derived from contraction of the hot nucleus, 

 decreased, the energy derived from the sun became more 

 efieetive, giving rise to changes wherein variations of tem- 

 perature and the circulation of air and water over the sur- 

 face of the earth would come into play. It is to these — 

 to the solvents of the atmosphere and rain, to the driving 

 wind, to water in its several states and movements, whether 

 of disrupting frost, grinding glacier, eroding rivei-, or waves 

 and currents of the sea — that the five-and-twenty miles and 

 more of stratified rocks (for the same stuff" has been used 

 over and over again), with all the varied contour of the 

 earth's surface, are mainly due. 



Vast, slow, and continuous as are the changes, they occur 

 within defined limits. The deep ocean basins, the lines or 

 seams of the great mountain chains, have probably been per- 

 manent from the remotest geological epochs, and the variations 

 in land and water distribution have been confined to certain 

 areas. All the evidence fui'nished by the aqueous rocks, 

 from the earliest primary to the alluvial formations of 

 to-da}', point to their tranquil deposition on the floors of 

 relatively shallow seas, where they have been converted by 

 pressure and other means into solid beds, entombing organic 



