21072 Popular Educator. VOLUME THE FIFTH. STUDIES serve for delight, for ornament, and for ability. Their chief use for delight, is in privateness and retiring; LONDON: W. KENT AND CO., 51, AND 52, PATERNOSTER ROW. MDCCCLVI. As we have already informed our readers, it was our intention to have closed the POPULAR EDUCATOR with the Fifth Volume. Finding it impossible to do so without leaving several subjects unfinished, we determined to carry on the Work to the end of the present year, and then issue a Title and Index to be bound up with the enlarged volume. Since that time we have received so many strong expressions of regret at the early discontinuance of the publication, that we have been induced to postpone its termination till the completion of the Sixth Volume. We, therefore, at the request of several correspondents, now present our readers with a Title and Index. for the convenience of those who may desive it. Rules on Expressive Tone; Appropriate Modu- lation; Promiscuous Exercises: Antiquity of Freedom; Pope and Dryden....... Promiscuous Exercises: the Puritans; Univer- The Upright Lawyer; Human Culture; Ameri- can Eagle; Memory; Old Ironsides...... 229 Interesting Adventure; Thoughts on Polite- ness; Ūde on Art; GoD; Niagara Education of Females; Custom of Whitewash- ing; Child of the Tomb; Love and Fame .. 274 XIX. Poetry; Causes of War; Foundation of National Character; Success of the Gospel; Power of LESSONS IN GEOLOGY.-No. LI. BY THOS. W. JENKYN, D.D., F.R.G.S., F.G.S., &c. CHAPTER V. THE CLASSIFICATION OF ROCKS. SECTION IV. (Continued from page 316, Vol. IV.) ON THE TERTIARIES. II. ON THE FOSSIL REMAINS OF THE TERTIARIES. ALL the beds of the tertiary rocks have every appearance of having been deposited in a shallow sea, not far from coast lines, with much regularity, and in the course of many ages. The earlier beds are very extensive, and consist of rolled pebbles produced by the rubbing and wearing down of the chalk flints, and perhaps of fragments of hornblende and primitive rocks, scattered over a shallow sea-bottom. It is otherwise impossible to account for the immense beds of sand found in the tertiaries. To enable you to derive intellectual advantage from this lesson on the plants and animals of the tertiaries, your mind must keep firm hold of the following principles: 1. The term "tertiary" implies a "secondary" system of rocks as already in existence. The highest and newest of these is the chalk, 2. The "secondary" beds may have formed either the bottoms of seas, or islands and mainlands, for many ages before the tertiaries began to be deposited. 3. During this interval, all the districts that now form the great plains of Europe were covered by the sea. 4. Most of the European land of that epoch lay chiefly from east to west, and extended far into the Atlantic, connecting the land now called England and Ireland not only with Spain, but also with the islands to the west of Africa. 5. At that time the Pyrenees, the Alps, Apennines, the Grecian Mountains, the Caucasus, the Carpathians, etc., formed a chain of islands in the open sea. 6. Things continued long in this tranquil state until a volcanic power threw up the Wealden of Kent and Sussex, and a gradual upheaval of the land took place, and the aforesaid islands rose gradually higher and higher above the ocean, and consequently more land was formed. 7. As those vast islands rose, the sea would dash against their sides, dislodge fragments from their cliffs, which they would roll smooth, wear down, until they constituted the beds of gravel which now cover the chalk in some places. 8. The shores of these islands and mainlands were low and swampy, and large rivers brought down the mud and sand to form what is now the south-east of England, and also the formations about Brussels. 9. The seas were tenanted by animals like the shark, and by fishes of the tribes now found in warm latitudes, and by large shell-fish that could live either in salt, or in brackish, water. 10. The rivers were peopled with crocodiles, turtles, tortoises, something akin to those now existing. 11. The sides of the hills and the plains were clothed with a rich tropical vegetation, abounding with the palm-tree and the cocoa-nut. This luxuriant vegetation indicates an abundance of animal life. These geological facts, and others akin to them, will help you to understand some of the peculiar circumstances in which you occasionally find the tertiary deposits. The upheavals VOL. V. which took place during the tertiary epoch will explain the inclination or dip which mark the strata in some localities. The scooping or denuding action of the ocean upon the chalk beds will explain the hollows or the basins in which the tertiary formations rest. VEGETATION. In the basins scooped by denudation in the chalk, and which are now called the Basins of London, Hampshire, the Isle of Wight, and Paris, the Eocene beds always consist of a coarse pebbly gravel, at first spread pretty uniformly over the whole tract; but afterwards, when the and became more elevated, and consequently the rising rocks yielding different kinds of detritus, its character altered. If you imagine cliffs of rocks of different characters, thus gradually rising, and being constantly acted upon by the waves of the sea or by running water, and this water-action taking place in circumstances of great diversity, you will come by the facts which will enable you to account for the coarse limestones of Paris, the plastic clay of London, the marly clays of Brussels, the silicious or flinty formations from the warm springs in Auvergne in Central France, and for the various limestones of the Greek Islands. That the vegetation of the first tertiary land, or the Eocene, was very luxuriant, is proved by the fragments of wood and the fruits of trees which are found fossil in rich abundance in the Isle of Sheppey at the mouth of the Thames. These fossil woods are very great in number and very rich in variety. Even in the Isle of Sheppey alone, several hundred species have been discovered, all of them differing much from existing plants, though they are closely allied to some which are now found growing in warm climates. There is a large preponderance of a species allied to the palms, something like a kind between the cocoa-nut and the screw pine or Pandanus, which are so well known in tropical climates. There are others of the Nipe family, which now luxuriate in Japan, and in the Spice Islands. The fossil wood of these trees is often found to have been pierced, and almost destroyed, by an extinct kind of Teredo, before it had been deposited in the mud. Sometimes the wood presents nothing but cavities, which had been left by these animals, and which were afterwards filled up with carbonate of lime. SHELLS. The tertiary beds abound in shell animals, both univalve, having but one shell like the snail; or bivalve, having two shells like the oyster or cockle. The bed called the London clay is full of.the remains of crabs and lobsters, some of which are very perfect. One of the most remarkable groups amid these tertiaries, is a species of foraminiferous shell, called the nummulite on account of its resemblance to a small piece of money. The fossil remains of this shell-fish are so incredibly abundant in some localities, as that rocks of enormous size are entirely made up of them. The tertiary shells bear, for the most part, a considerable analogy to those which exist at present, as will be seen in Fig. 1. Our engraving is only intended to represent a few specimens of the tertiary shells, to show their usual appearance and character. The entire species, as already determined by naturalists, amount to nearly three thousand. Some of the tertiary strata are almost entirely composed of shelly remains in a broken and crushed state, and many sandy seams in the clayey beds consist of shell dust. In some places the shells are pre105 |