epoch. I am found at the surface, surrounded by rocks of every age, even including those of the Tertiary. Wherever the pent-up force of the earth's interior has thrust us up, there have we slowly elevated the rocks lying upon us. In many cases this elevation has been so slow that it has hardly exceeded the rapidity with which these overlying rocks have been gradually worn away! Think of the vast antiquity of the earth's crust, as indicated by these facts alone! Since the granites of the Highlands of Scotland were formed, twelve miles of overlying material must have been removed! Where has it all gone to? Ask the nineteen miles in thickness of the known stratified rocks, all of which have probably been formed since that granite itself. You scarcely need be afraid of Time, when you have Eternity to draw upon!

66

CHAPTER II.

THE STORY OF A PIECE OF QUARTZ.

"God worketh slowly; and a thousand years
He takes to lift His hand off. Layer on layer
He made earth, fashioned it and hardened it
Into the great, bright, useful thing it is;
Its seas, life-crowded, and soul-hallowed lands
He girded with the girdle of the sun,
That set its bosom glowing like love's own
Breathless embrace, close-clinging as for life;-
Veined it with gold, and dusted it with gems,
Lined it with fire, and round its heart-fire bowed
Rock-ribs unbreakable; until at last

Earth took her shining station as a star,

In heaven's dark hall, high up the crowd of worlds."
BAILEY'S Festus.

ACT," they say, "is often stranger than fiction." I do not think you

will find this old saw better illustrated in the whole series of geological teachings than in my own history. That history is connected with one of the grandest discoveries of late years, inasmuch as it carries back the antiquity of the globe even beyond the mighty ages which had already been claimed for it. Indeed, the practical effect of this is to show the geologist that time, as a factor, has nothing to do with his investigations. That simple relation in the succession of events is all

he can safely arrive at; and that his finite mind can no more conceive of the myriads of years which are included in the world's biography, than it can sum up in human arithmetic the stars and systems which crowd the illimitable realms of space! Within the last ten years a clearer geological knowledge of my origin has caused geologists almost to double the already known antiquity of the earth. At the time I mention, or thereabout, it was usually understood that the Cambrian period was the oldest and most primeval. The human mind is essentially conservative, and although geologists reasonably claim to be more catholic than most men, they are under the same influences. This is indicated by their unwillingness to make the world appear older than they possibly could help. Hence such terms as "Primary," "Primordial," &c. applied to the ancient strata-which nevertheless are all much younger than myself-are so many landmarks which have shown this tendency in the human mind. It may be, that although the geological formation to which I belong is undoubtedly the oldest known at present, in any country, subsequent research may eventually make known an older period still. The difficulty in doing so, however, will be considerably heightened by the fact of all these oldest rocks having passed through many changes, by heat and chemical action, so that nearly all traces of their former fossils are effaced, and thus they are reduced to a similarity of mineral condition all the world over.

There are few of my readers who are not acquainted with my general appearance. They have gathered me as a milk-white pebble by the seabeach, or have admired me as they climbed the Scotch mountains and saw me sticking out of the contorted rocks like a huge white rib. Or, they may have been more pleased still with the geometrical shapes which my substance is capable of assuming as a six-sided, pointed crystal. It is of my former state, rather than of my latter, that I intend now more particularly to speak. And yet it is necessary for me to say that there are two common conditions in which I am usually to be found. One is as Quartz, the other as Quartzite. These terms are merely significant of appearance, and include little or nothing of chemical difference. Quartz proper is usually found in veins, having been forced into fissures when it was in a soft, heated condition. Quartzite has not so completely lost all its original structure, and its particles or grains may often be seen retaining their original water-worn form. Again, Quartzite does not occur as an intrusive rock, but in huge stratified masses, hundreds of feet in thickness. And yet you may find transitions in these two extreme states of my family-even from the transparent crystal condition of the "Brazilian pebbles" to the coarse-grained and resinous appearance of quartzite.

Let me be thoroughly understood. Although I am representing that great, and at present oldest

epoch in our planet's history-the Laurentian-I should not like you to fall into the mistake of supposing that I am limited to it alone. On the contrary, formations of much more modern date than that to which I belong are rich in quartz veins and even beds. In short, any rock that has been exposed to the same influences as myself, if it contained the same chemical substances, would also become quartz as the result. They tell me that I am chemically composed of only one substance— Silica. My normal condition is transparent and colourless, although I am rarely found like this except when in geometrically-shaped crystals. A milk-white colour is that which I commonly affect, and this is due solely to the rate at which my parent mass cooled down. Hence it is that geologists can more or less tell from my appearance the circumstances which attended my birth. From the pure, transparent condition I mentioned above, I pass through a great many modifications, and in each stage of these I am known by different names. But with the exception of very slight mixtures of other ingredients than this silica, I continue the same throughout; thus, when I am of a violet tint I am called Amethyst; when of the colour of sherry, Topaz; when of a smoke-brown hue, Cairngorm, &c. Mixed with other chemical substances I pass into jasper, flint, chalcedony, agates, &c., in all of which you will find that the largest portion of their whole bulk is silica.