The delicate actiniæ and the rarer sea-weeds cannot be obtained in winter; but the pebbles, which are intended to form the subject of this little book, may always be met with; and the changes induced by rough winds and surging tides, yield them in even greater abundance.
The pleasure of collecting pebbles has been greatly enhanced, to my mind, by considering how it is that we come to have pebbly beaches at all. Inevitable as these may appear to some people, they are quite a phenomenon in their way, and to the full as deserving our attention as the colony in a rabbit-warren.
Originally, the land alone possesses such materials; but it is the sea which finds them out; and these two facts, put side by side, have sometimes reminded me of the arbitrary allotment of the sexes in the old mythology. Oceanus being an enterprising gentleman. Terra (always feminine) is the quiescent lady, to whom he pays his court. She carries a prodigious number of these treasures in her flinty bosom; but it is only he, and his friends the rivers, who can get at them and draw them forth. In our English Channel, Ocean is as fond of doing this, and of fringing his waterline with a brown pebbly border, as other gentlemen are, now-a-days, of wearing, if possible, a beard like that of the Sophi. Nor is this surprising, when we remember that all creatures naturally desire something which they have not got. For the bottom of the sea itself is no beach at all, but chalk or sand, and sometimes hardened sandstone, with, I dare say, many precipitous pits and hollows, and many pointed crags. Here, gigantic fronds of the oar-weed wave to and fro among thousands of acres of dulse and bladderwrack; while porpoises and dog-fish dive, and limpets and mussels crawl, and arrowy lobsters shoot through the cerulean gloom, and (if Mr. Tennyson may be believed) mermen and mermaids play at hide-and-seek. Wonderful things there must be, if we could only spy them out; but I do not think many pebbles. Whereas, our mother Earth teems with these latter. There are jaspers in the conglomerate, and agates in the mountain rocks, and veins of porphyry and serpentine in the trap and basalt, and garnets and sapphires in the granite, and flint-nodules in the chalk, and quartz-crystals almost everywhere. Probably these exist, also, in many of the submarine strata; but unless a volcanic eruption should occur, there is no force in operation there to dislodge them. The bed of the ocean, and all depths of it below a hundred feet perpendicular,[2] as divers well know, remain calm and still, even when a tempest is raging above. But on what we are pleased to call “terra firma,” the case is reversed. Solid as the ground appears, all is subject to elemental change and motion; and whenever the waves of the sea or the strong current of a river can plough some crumbling chine, or wear away the face of a cliff, down come the imbedded pebbles and crystals, and gradually form a beach upon the margin of the ocean. And this beach is tossed up and down, and rolled to and fro, until most of the stones composing it have become as smooth as hazel-nuts.
The above may be rather a rough sketch of the source of a beach; but I believe it is correct in its leading features. In a subsequent chapter we may better note certain peculiarities which are more than meet the eye.
But what are the pebbles themselves?
Most persons have occasionally handled specimens of the precious stones or “gems;” but few of them, perhaps, are aware that our pebbles of the road-side and sea-shore claim a common origin with these dazzling crystals. Such is, however, the fact. Chemical analysis, availing itself of the blow-pipe, the solvent acids, and the voltaic battery, has succeeded in determining the base of every known gem. And the earths which furnish such bases are chiefly two—ALUMINA, or clay, and SILICA, or pure flint. From these, with an admixture of lime, and sometimes of iron, in small quantities, all the native gems are derived, with the exception of the diamond, whose base is CARBON.
Intensely hard as these substances are, and apparently not susceptible of change if left to themselves, they have probably passed through great chemical changes in the silent laboratory of Nature. For it is supposed that our operations in analysis, if carefully conducted, merely bring back their subjects, by a kind of reversing process, to their several primitive bases.
Now it is evident that the commoner pebbles are derived from these same earths, of clay or flint, albeit in a debased condition. For there is nothing else of which they could be made: neither do they exhibit any properties foreign to those which such substances possess. Yet, how vast is the difference between an oriental gem and the brightest production of clay-pits or granite rocks. Not greater, however, than that between Damascus steel and coarse pig-iron; or, between French lawn and sail-cloth. And if Art can work such distinctions, why not Nature?
In fact, a perfect gem is a master-piece which chemistry and crystallization have combined to elaborate, and which man has ransacked the corners of the earth to obtain. The deep has been made to surrender its treasures to the diver or the sunken net: the rock has been blasted, and its inmost vein searched: the rushing river filtered, and its sand sifted: and the contents of the jeweller’s caskets are the result. Here may be seen diamonds from Golconda; and rubies from Samarcand and Pegu: sapphires, emeralds, and amethysts from Persia, Arabia, and Armenia: the topaz, blazing like fire, from the Indies or from the Ural: the turquoise, with its delicious blue, from Arabia and Palestine: the opal from Honduras: the blood-red garnet and amandine from Bohemia, Ceylon, and Greenland: the jacinth and the chrysoprase, the chrysolite and beryl, with pure pearls of globular form, all from the land of the rising sun, while a deep brown jasper, rayed with stripes and rings as black as jet, has travelled like a wandering palmer from sultry Egypt or the terrible desert of Sinai.
To form and perfect the finer crystals, extremes of heat or cold appear to be necessary: whereas our clime has perhaps always been temperate. Beside this, it is probable that the mother-earth is not found pure with us. There is a kind of white clay, called “kaolin,” obtained in one particular quarry near Meissen in Saxony, and met with nowhere else. From this clay the exquisite Dresden porcelain is baked, and this clay cannot be exactly imitated. A near approach to it has been made by mixing good potter’s clay with pounded chalcedony-flints; but still the biscuit so produced is never equal to that from the “kaolin.” In like manner, we may suppose that the peculiar earth which exists in sapphires no longer occurs in our post-tertiary clay-beds.