the hollow shell-cast be filled entirely with flint. All these are possible changes, and changes that every day present themselves to the eye of one who studies the forms of ancient life.

FIRE-FORMED ROCKS.

The fire-formed rocks form a class distinguished from all other systems by their not possessing fossils, and the evidence they possess of their origin by the agency of fire. Little is known of the earth's interior, but much has been conjectured, and for many years the majority of geologists have held the opinion that matter in a state of liquid fire forms the earth's centre. This internal fire was originally derived from the earth itself. In that far-distant "beginning," before the present state of the earth came into existence at the fiat of the Almighty Creator, the earth was a revolving globe of fire, which had been a portion of the sun, but was afterwards detached from that body. As this fiery globe cooled, a solid crust was formed, and age by age the crust has increased in thickness. At times, however, the fire makes its presence known, and bursts forth through the earth's safety-valves-the volcanoes.

Granite is found in all quarters of the globe. It underlies all rocks. It forms the base upon which all the others rest. Granite differs from granite, even as one stratified system differs from another. The name is a general one.

Space does not allow more to be said about these important rocks, but their value will be appreciated when it is mentioned that they are the chief depositories of the world's mineral wealth, and that all the great mountain-ranges are mainly composed of granite.

Volcanic Rocks are the formation of recent times. They occur in the vicinity of volcanoes. The molten matter that pours forth "from the bowels of the earth," assumes different appearances in accordance with its rate of cooling. Tons and tons of lava pursue their course down the sides of Vesuvius during an eruption.

Lava, after cooling, much resembles the slag from a furnace. The solidified froth or scum forms pumice, a light-coloured, spongy-looking substance, a useful substance for polishing purposes. Both soft porous earths, and dark close-grained rocks have been formed with molten lava. The ancients obtained a peculiar glasslike substance from lava; they called it obsidian, and used pieces of it as looking-glasses.

To enumerate the mercantile products obtained from the fire-formed rocks, would be to enumerate every mineral product that is valuable for commercial purposes. From Sicily and Italy we obtain our chief supplies of sulphur and borax. Granite rocks supply us with the best building and road-making material.

METAMORPHIC ROCKS.

Pressure, as we all know, produces rapid changes in any substance which comes under its influence. Place a heavy weight upon clay or sand, and watch the results. The pressure developes heat, the augmented heat produces change.

The finest marble for making statues is that from Carrara, in Northern Italy. There for centuries has this wonderful stone been quarried. In the time of Julius Cæsar it had obtained renown, and still sculptors use it in preference to all other varieties. Carrara marble has a beautiful white colour, and is perfectly pure, except where covered by gray veins.

This splendid marble is only ordinary consolidated lime, whose particles have become changed in form by their subjection to heat. Whence came that heat? Was it heat communicated from the earth's interior, or was it heat developed by pressure?

Once men thought these splendid marbles formed portions of the original matter of the earth. They asserted that these changes were effected before the creation of living beings. But careful examination of the localities where they occur does not warrant this

supposition. It shews, on the contrary, that they were originally limestone belonging to the later system. Hence the present condition of the limestone was obtained during one of the last ages of the earth's history.

The Carrara marble rests upon beds of talc-schist and muca-schist. But these schists are only rocks that have

been subjected to change.

Thus, this series which many deemed so old, consists of ordinary stratified rocks, which have changed in appearance.

FOSSILS.

Fossils are the guides by whose aid alone the true classification of rocks can be learned. Without them, we are completely "at sea," for the mineral structures of the various strata so resemble each other that we could not really, by their help alone, arrange the strata into the various systems. Fossils are the keys which enable us to unlock the doors of geology, and to discover the great truths which were concealed from human knowledge by man's own want of research for such a vast number of ages.

The word "fossil" is derived from a Latin word, which signifies "dug up." It is applied to any vegetable or animal substance that has become wholly or partially petrified. Now, we wish to see what kinds of beings are found in this state,-what were the great types of life that existed in those first ages of our earth's history.

The earliest forms of life detected in rock-masses are of the lowest class. The tracks of worms, the borings through sand, and the traces of heavy falls of rain, are the first signs that the earth began to assume a definite form, and its curiously punctured roots ramifying in all directions. Beneath the shades of these huge trees grew undergrowth, rivalling in extent and density that found in Tropical South American forests at the present time. Ferns of great height and of endless variety abounded in every direction.

Then think of the mighty change that passed over our land as these forests gradually, slowly but surely, sunk lower and lower, became portions of the sea-bottom and were surrounded by heaps of sand, until changes were rapidly effected. The trees decayed, and, in process of time, formed beds of coal-beds revealing, in their method of occurrence, in their mineral constitution, and in their fossil contents, the mighty changes produced by Time.

Centuries past, and again a change passed over our little England. The land was once more released from its watery prison. And over it roamed animals resembling in many respects our crocodiles, but more dreadful appearance, constructed on a larger scale, and possessing an apparently insatiable appetite. Then lived the original of the dragon, the half bird and half reptile, whose petrified remains still fill us with wonder and astonishment.

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Such are the scenes that fossils enable us to conjure up. Such the state of the world at two epochs,-the carboniferous and the new red sandstone.

YORKSHIRE.

PART I.

"THE vale of Yorkshire is the richest and most extensive valley in Britain, if not in all Europe," contends Drake. And it is affirmed by another writer of even greater antiquity, "Nay, for there is no place out of London so polite and elegant to live in as the city of York."

With due reservation for local prejudices, it may be justly conceded to Yorkshiremen that no county in England possesses in greater profusion such rich and perfect examples of every variety of scenery. We find alike rich old sward and pasture-land, fertile corn-fields,

well-timbered forests, plenty of thick black fir plantings, with shelter for all sorts of game, clear hill becks abounding with trout; rivers, either broad, fair, and navigable for the greater part of their course—as Ouse, Derwent, and others or chiefly rocky and picturesque, escaping from the moutains, and running along the valleys which, in olden times, the sea channelled out for them-as Swale,* Esk, Rye, Ribble, Lune, and the northern half of the Tees. The grouse, plover, and lapwing cry and wail on endless ranges of moor, which, purple and yellow in their season, are yet so black and dreary for the greater part of the year as to leave their mark in the very names of the surrounding district; thus we have Helmsley Black-a-moor, Whitby Black-a-moor, Kirby Moorside, &c. While of other names bestowed, either in apparent reference to some horrible crime or tragedy now forgotten, or specially to indicate the rugged and gloomy character of the surrounding scenery, there are numerous examples-such as Bloody Beck, Black Hambleton, Hellgill, Black Brow, Wild Boar Fell, Black Holes, Hell-Pot, Cauldron Snout, Hagg Holes. Again, Baldersdale, Balder Beck, Woden Beck, and Woden's-croft are names clearly derived from the Scandinavian gods of our ancestors, and are relics, or fossil words, which in themselves alone convey a history.

There are ranges of round, green-covered chalk hills called wolds, as well as innumerable crags, nabs, cliffs, scars, heads, peaks, toppings, edges, fells; these being all local term signifying abrupt heights. Thus, Brimham Crags, Eston Nab, Whitestone Cliff, Goredale

*Many of these rivers are spoiled, so far as angling is concerned, by the reprehensible practices of the servants of the leadmining companies. The lead is separated from the crusted ore by washing; the water is drawn from the nearest beck or pond, and the crushed stone is carried down by the beck to the nearest river, looking about as thick as a glacier stream. This poisonous wash is discharged at a certain hour; the waters of the river are immediately changed from clearness like crystal to a murky leaden hue, and shortly afterwards the fish are drugged and stupified, and half of them lie dead and floating on their backs.