GEOLOGY. 



wholly a marine deposit. The land we know little 

 or nothing of; sufficient, however, to shew that it 

 was clothed with vegetable life, as in other periods, 

 (but little to picture its appearance. Over it, huge 

 Wealden reptiles sought their prey, birds flew, 

 and great apes swung from tree to tree. But the 

 ocean swarmed with varied life, mild sea-breezes 

 blew, and smiling sunbeams sparkled upon its 

 waters ; for the climate was warm, as shewn by 

 the corals, reptiles, and monkeys. In the tepid 

 waters lived numberless fishes and shells, and on 

 their surface the nautilus spread its coloured sail. 

 The origin of chalk is a problem not yet satis- 

 factorily settled, but the generally received opinion 

 is, that the shores were fringed by coral reefs, 

 which the dashing waves gradually wore down 

 into fine powder, as they still do in tropical seas ; 

 \\hile millions of shell-fish teemed in its waters, 

 and left their white shells as an impalpable sand, 

 that, under the microscope, shews the tiny houses 

 of the old inhabitants as perfect as on the day 

 they died. Flint seems mostly to consist of concre- 

 tions round sponges, corals, and other substances. 

 It may be found at any epoch, and occurs in 

 many other formations besides the Chalk, though 

 there in greatest abundance. 



X. TERTIARY SYSTEM. 



We have now arrived at a new epoch in the 

 Tiistory of the rocks, known as the Epoch of 

 Recent Life. Henceforward, the plants and ani- 

 mals bear not only a close resemblance to those 

 now existing, but a great proportion of them are 

 identical. We discover real exogenous trees, the 

 same corals, crustaceans, and shells, equal-lobed 

 fishes, birds, and mammals of existing families 

 and all these not only more numerous than 

 hitherto, but also more perfectly preserved. The 

 name given to this system is a relic of the names 

 used in early geology, when all rocks were divided 

 into Primary, Secondary, and Tertiary. In the 

 Tertiary System, two great periods are easily 

 distinguishable : I. The Warm Period; 2. The 

 Cold Period. 



i. THE WARM TERTIARY PERIOD. This 

 system exhibits clays, sands loose or hard, gypsum 

 or plaster of Paris, and marls. The only true rock 

 is limestone, made up of innumerable little shells, 

 so numerous, that the rock is named, from its 

 tt?/-like shells, nummulitic, 1 and is extensively 

 found throughout the world. The limestone is 

 burned for various purposes ; the clays are exten- 

 sively used; the harder sands are employed for 

 building ; and amber is also found. The strata 

 occur exclusively in patches known as basins, 

 the London and Paris basins being the most 

 important. 



Fossil Remains. The remains are both numer- 

 ous and important. Of plants there are few 

 marine specimens, as these seem to have been too 

 tender to be preserved. We find, however, mosses, 

 palms, ferns, leaves, fruits, seeds of different kinds, 

 and whole pods of pea-plants. We have real 

 exogenous timber, with specimens of palm, cypress, 

 and fir. 



The animals resemble or are identical with 

 existing species, and the Tertiary System has been 

 -divided into periods according to the percentage 



1 From Latin numntus, a coin, and Greek lithas, stone. 



of life-remains. We have corals, star-fish of the 

 same species as those existing, and the shells are 

 very beautiful, finely preserved, and scarcely dis- 

 tinguishable from those to be gathered on our 

 present shores. 



Among the fishes, we find various species of the 

 shark, ray, sturgeon, sword-fish ; and of fresh- 

 water kinds, the perch and the carp. Among the 

 reptiles there are the crocodile and alligator, and 

 the turtle. Birds are numerous, one specimen 

 found in the Paris basin being gigantic. Mam- 

 mals are found of every existing order, amongst 

 others, the whale, elk, stag, antelope, camel, llama, 

 tapir, hog, rhinoceros, hippopotamus, beaver, hare, 

 squirrel, monkey, elephant, horse, tiger, and hun- 

 dreds of others. So numerous are these remains 

 in some parts, that one rock in Norfolk is known 

 as the Mammaliferous Crag. But the most 

 remarkable of the ancient animals are the huge 

 monsters whose skeletons, carefully reconstructed, 

 may be seen in the British Museum, some of them 

 above 10 feet high, and 20 feet long. The most 

 wonderful is the mammoth, with two great tusks 

 like an elephant. Others are the dinotherium 1 or 

 ' fierce beast,' the megatherium 2 or ' great beast,' 

 and the mastodon? In different parts of the world, 

 including many places in England, remarkable 

 caves are found filled with bones of various ani- 

 mals in clay or sands, known as ' bone-caves.' 

 These caves have some of them been the dens of 

 savage tigers and other brutes, the bones of their 

 prey being still found; some have formed the 

 abodes of different creatures at different times 

 who have lived and died there ; while others have 

 had their contents washed into them by floods. 



Scenery. During this period shallow seas 

 rolled under a genial sun, in which low islands 

 rose crowned with palms, while the savage shark 

 and sword-fish swam in the surrounding waters. 

 The elephant ranged through the tall groves on 

 shore ; the hippopotamus wallowed in the fresh- 

 water lakes ; the rhinoceros crashed through rank 

 jungles ; the mastodon, mammoth, and tapir trod 

 in forests of palm ; and the wild ox and buffalo 

 roamed over wide grassy prairies. 



2. THE COLD TERTIARY PERIOD. Immediately 

 above the strata just described, with these strange 

 organisms that speak of a warm climate, are found 

 remarkable accumulations of sand, often found 

 pure in hillocks ; gravel, and clay interspersed 

 with rounded worn boulders, known under the gen- 

 eral title of the ' Boulder-clay,' some of the boulders 

 being of enormous size. From various phenom- 

 ena, it has been proved that the climate became 

 arctic in character, and our country and others 

 were enveloped from shore to shore in a vast ice- 

 sheet, like the Greenland of to-day. From the ends 

 of this huge ice mantle, immense masses broke off 

 and floated away as icebergs. By and by, how- 

 ever, the climate became milder, and Britain looked 

 like Norway and Iceland, with glaciers on the 

 higher grounds, reaching here and there to the 

 sea. Gradually the great ice-fields melted away 

 under the rays of the genial sun, and our country 

 looked like the present Switzerland, till at length 

 the last glacier disappeared from the highest hills. 

 The effects of all the wear and movement of these 



l From Greek deinot, terrible, and tfcriffit, beast. 

 From Greek megas, great, and thirion, beast. 

 From Greek mastas, a nipple, and odous, odontot, tooth, 

 from nipple-like projections on its grinders. 



