In some instances in dry ravines, where slate rock occurs, it is decomposd into clay, to a considerable depth, from the vast amount of time elapsd since it has been placd in its present situation. Where such decomposition has occurd, it is useless to penetrate downward into it, in search of gold, as the gold was deposited most generally in a strong iron deposit, previous to the decomposition of the rock. This strong iron deposit is formd of soluble iron, amongst which the gold is mechanically entangld and there held, unless the iron becomes again soluble and leaves the gold to settle down by gravitation into the decomposd rock below. Cases of the second solubility of the iron do not often occur in dry ravines.
Mode of Searching for the Second Variety.
It is more difficult to point out a successful mode of searching for gold of the second variety than either of the other two. Yet notwithstanding the difficulties attending it, some hints may be given, useful to the miner, who has previously become in some degree acquainted with the philosophy of running water and the nature of tertiary deposits.
Those creeks of intermediate size between dry ravines, and the large rivers flowing down from the mountains, though dry or nearly so at some seasons of the year, are powrful in times of heavy rains or the rapid melting of snows, as is evident from the position of some heavy rocks in those streams, which none other agent the powr of a mighty stream could have placd there.
In prospecting for gold in those creeks, the miner may select a position which he judges to be the channel of the creek, or that portion of it where the greatest powr of water is exerted, and commence digging downward, till he arrives at the rock over which various tertiary sediment has flowd, and if he finds the coarse gravel and sand through which he passes, entirely down to the rock, cleanly washd of alluvium, he may fairly conclude that he is in the current of that stream, or where the water passes with greatest force. In those situations, he rarely finds gold, or if he does, it is in sparing quantities.
If upon arriving at the rock, he finds a cross reef or ledge rock, rising one foot or more above the rocks downward stream from his position, he may then prospect outward either way toward the banks of the creek, keeping close to the rock on the lower side, till he arrives a little outward from the current where the waters formd an eddy, as denoted by a mixture of alluvium with the sand and gravel of the creek. In those situations, he may expect to find gold. If he finds gold in such a locality, he may prospect outward toward the banks of the creek, till he has exhausted the whole deposit.
As the tilted rocks of the gold district have universally one course, and as creeks meander across them in nearly every possible direction, there are chances in many places for reefs of rocks to traverse the beds of creeks, directly along their channels. Under such circumstances, but little gold has been deposited. If the miner continues his search along the creek downward, till he arrives at a bend in it, where the water is forcd over such reefs, a little outward from the channel, gold is often found in great abundance—watching carefully whilst excavating the earth in such places, to prospect the lower side of any reefs that may be found there.
If a rock of several feet in hight traverse crosswise the whole width of a creek, so that the only passage for the water of the stream is over it, like the fall of a mill-dam, its force seldom allows gold to be deposited near to it. But a short distance below, where the first quiet waters occurd, gold may be found in lateral and central pockets and little basin-shapd hollows of the rock at the bottom of creek deposits.
Again, if a rock project from any portion of the stream, so high that water cannot run over it but is forcd around it, an eddy is in such case formd immediately below it, in which situation gold may be expected to be found.
In some situations, along some of the creeks, as at Sullivan’s camp, on one of the tributaries of the St. Waukeen, the slate rock, on which the gold was deposited, has since been decomposd to a considerable depth below the tertiary deposit. It would seem that a second solubility of the iron deposits had taken place, and liberated the gold to settle down into the decomposd rock. In such situations, the miner continues to prospect downward, as long as he finds gold abundant enough to reward his labors.