50 



* KNOW^LEDGE ♦ 



[January 2, 1888. 



arctic regions had a mild climate, but towards the close of 

 the long-lasting periods of the Tertiary age snow and ice had 

 spread, not only over the whole of the arctic regions, but 

 even over parts of the European and American continents 

 ■which at present are free from them. This, however, must 

 be regarded as indicating only a temporary extension of the 

 northern snows and ice. Even during eras belonging to 

 the close of Tertiary time the earth possessed on the whole 

 a warmer and more equable climate in high latitudes than 

 she has now. 



The vegetation of the earth now began to resemble closely 

 the vegetation of the present day. Nearly all the genera of later 

 Tertiary vegetation still throve on the earth. Animal life began 

 also to resemble the animal life of to-day much more closely 

 than duiing preceding eras. Mammals not only made their 

 appearance on the earth, but, as usual with successful in- 

 coming types, they showed at the outset of their career a 

 richness and fulness of development such as they do not 

 present in these times. The pachyderms, still the largest of 

 the land mammals, were much larger in Tertiary times than 

 now. In Tertiary ages, also, gigantic cetacean sea mammals, 

 the ancestors of the whales, dolphins and kindred races of 

 our own times, gradually took the place of the monstrous .sea 

 saurians of preceding ages. 



The division of Tertiary time into Eocene, Miocene, and 

 Pliocene periods indicates the recognition among geologists 

 of the growth and development of modern forms of animal 

 and vegetable life during the Cainozoic eras. For these 

 names imply simply '• Dawn of Recent," " Fewer Ilecent," 

 and " More Recent," '■ forms of life " being undei-stood. 

 The lower Tertiary strata are called Eocene to show that 

 recent forms of life begin to be recognised in those strata; in 

 the Miocene strata recent forms of life are more numerous 

 than they had been but still not so numerous as the ancient 

 forms, while in Pliocene recent forms have not only in- 

 creased in number but they now exceed the ancient forms, 

 and in gradually increasing degree, till as we are passing 

 from the upper Tertiai-y to the lower Quaternary or recent 

 strata we have to change our descriptive term from Pliocene 

 or more recent (than ancient) to Pleistocene, or mostly 

 recent. 



In considering the Flora of the Eocene period, we are 

 chiefly struck by the evidence it affords of the extension of 

 a climate still tropical over regions now temperate, and of a 

 climate still warm over regions now intensely cold. Plants 

 now only found in the hotter parts of Asia, Africa, America, 

 and Australia throve then in Canada, Scandinavia, and 

 Siberia. Ferns and evergreens were numerous, but many 

 deciduous trees — elms, hazels, willows, planes, chestnuts, &c., 

 — had now made their appearance. The Fauna of this period 

 also indicates a generally tropical climate extending over the 

 temperate zones, and a temjjerate climate extending to far 

 within the arctic regions. Reptilian life was no longer so 

 preponderant as during Mesozoic time, the reptiles still 

 thriving in the Eocene period being chiefly turtles, tortoises, 

 and crocodiles, closely resembling those now existing. Re- 

 mains of birds are found more freely in Eocene strata than 

 in the lower formations, though avian fossils are naturally 

 not abundant in any strata, the power of flight saving birds 

 from most of those forms of death which favoured the pre- 

 servation of fossil remains. True mammals now made their 

 appeai'ance in great numbers. Small pony-like animals 

 appeared — the ancestors probably of the horse, ass, zebra, 

 and quagga, but differing from the modem equine races in 

 possessing most of the toe of each foot, whereas the Equus 

 of to-day possesses only the middle toe complete, the side 

 toes being represented only by rudimentary splints. Hogs 

 of various kinds, deer and antelopes, squirrels, lemurs and 

 bats had now appeared. Races also now seen for the first 



time, but not destined to last to our own day, throve and 

 multiplied during the Eocene period — creatures (the tino- 

 ceras and deinoceras) like the rhinoceros in structure, 

 but having six horns instead of two, and like the elephant 

 in size, were now the most powerful denizens of the forest. 



Throughout the closing part of the Eocene period, called 

 sometimes the " Uligocene " (or '"' Few-recent "), there was a 

 general though slow progress towards the condition found 

 during Miocene time, during which the Flora and Fauna 

 showed a marked advance towards the characteristic forms 

 of recent geological time. Still, however, even in the Mio- 

 cene agL, the forests which adorned temperate regions 

 resembled rather those found in India and Brazil than 

 the forests of middle Europe and other such regions now. 

 Beeches, laurels, oaks, and poplars, as well as magnolias, 

 myrtles, sumachs, mimosas, and acacias, were now abundant. 

 Through the forests ranged giraffes, deer, antelopes, three- 

 toed horses, wildcats, bears, sabre-toothed lions, monkeys, 

 and apes. The deinotherium and mastodon were doubtless, 

 however, the most powerful land animals ; the deinothei'ium, 

 as large as the elephant, with two immense tusks in the 

 lower jaw, curved somewhat like those of the walrus ; the 

 mastodon, a foi-m of elephant, but in some cases armed with 

 four tusks, two in the lower as well as two large tusks 

 in the upper jaw. The forms of insect life also were par- 

 ticularly rich, especially the wood beetles, which attained 

 often singularly large dimensions. Frogs, toads, lizards, 

 and snakes were also numerous in the Miocene period. 

 Large cetaceans traversed the Miocene seas (their ear-bones 

 are found in considerable numbers in the raised sea-beaches 

 belonging to this part of Tertiary time). 



In Pliocene times, as the name implies, modern forms of 

 vegetable and animal life had become still more common. 

 Tropical types of vegetation were no longer found in the 

 higher temperate latitudes, and the forms gradually ap- 

 proximated more and more in character to those now 

 occupying the corresponding regions. The Fauna also pre- 

 sented similar characteristics. Tribes of animals roamed 

 over Europe in the earlier portions of the Pliocene period 

 which are now found only on the southern side of the 

 Mediterranean. In England, even in the latter part of 

 Pliocene time, the hyena, rhinoceros, elephant, and other 

 animals, now limited to tropical or sub-tropical regions, 

 must have been numerous to account for the frequency of 

 their remains. 



No definite dividing line can be drawn between the 

 Tertiary and Quaternary periods. The change from Eocene 

 to JSliocene, or from Miocene to Pliocene, corresponded 

 closely in character with the change from Pliocene to 

 Pleistocene. Ever since the time when life, vegetable or 

 animal, had first appeared on the earth, multitudinous forms 

 cf life had come into existence, had risen into greater or less 

 prominence according to their surroundings, and had in 

 some cases died out, in others had developed succeeding 

 races more or less closely akin to them, and in yet others 

 had continued scarcely changed even throughout the millions 

 of years which separate the beginnings of the Pala'ozoic 

 pei'iods from our own time. 



The steady advance of the stream of life, with its various 

 waves thus either dying out, or merging into other waves, 

 or progressing scarcely changed age after age, had gradually 

 led to the development of more and more of those forms 

 of vegetable and animal life which we regard as be- 

 longing specially to the present age of our earth's 

 history. For gradually the earth's surface had changed 

 from a condition utterly unlike what now exists to nearer 

 and nearer resemblance to its present aspect. At the be- 

 ginning the internal heat had extended its influence over 

 the whole surface of the earth, throughout the whole ocean. 



