By a great physical change the country was lifted out of the sea, either at once or by successive stages, and it presented then the appearance of a valley long and wide, covered almost everywhere by a deep clothing of sands, gravels, and shingles, with which were intermingled—not without some degree of method, but at various depths, and in various proportions—the lumps and grains of metallic gold which had formerly existed in the rocks, of which the sands and shingles had formed a part. And now the tiny streams, which had formerly terminated their short courses in the sea itself, flowed down the mountain slopes, united their waters in the bottom, and formed large rivers. These gradually cut their way into the superficial sands, washed them as the modern gold-washer does in his cradle, and collected, in certain parts of their beds, the heavier particles of gold which they happened to meet with in their descent. Hence the golden sands of the Sacramento and the San Joaquin, and of so many of the rivers celebrated in ancient story. But the beds of these rivers could never be the receptacle of all the gold of such a district. _They_ derived nearly all their wealth from the sands and clays or gravels they had scooped out in forming their channels; and as these channels occupy only a small fraction of the surface of the bottoms and slopes of most river valleys, they could, or were likely to contain, only an equally small fraction of the mineral wealth of their several regions. The more ancient waters had distributed the gold throughout the whole drift of the country. The river, like a “long Tom,” had cradled a small part of it, and proved its richness. The rest of the drift, if rocked by art, would prove equally, it might be even more, productive. It is in this old virgin drift, usually untouched by the river, that the so-called dry diggings are situated. The reader will readily understand that, while no estimate can be formed of the quantity of gold which an entire valley like that of the Sacramento and San Joaquin, or which wide sandy plains like those of Australia, may ultimately yield, yet it will require great sagacity to discover, it may even be that only accident and long lapse of time will reveal, in what spots and at what depths the gold is most abundantly accumulated, and where it will best pay the cost of extraction. We do not now advert to any of the other points connected with the history of gold on which our geological facts throw light. These illustrations are sufficient to show how rich in practical inferences and suggestions geological and chemical science is, in this as in many other special branches of mineral inquiry.