266 | GEOLOGY. 
This process, so new to all but Californians, is well exhibited at Michigan City, and will be 
briefly described. : 
The annexed engraving is from a daguerreotype of one of the claims, and shows their general 
appearance. On one side we see the bank, or bluff, formed by the drift, which has not been 
disturbed. The top of this bank is the general level of the surface, and was once covered by 
pine trees, as shown by the stumps and the treesin the distance. 
The frame, or staging, elevated above the surface, is a flume, or open conduit, for the water, 
and is highest in the back-ground, and the water flows towards the bluff, although in the picture 
thé descent appears to be in the other direction. At the end of this sluice a barrel is placed to 
receive the water, and a long hose-pipe of leather is attached to its bottom, and extends down 
along a favorable part of the bank to the level of the bed-rock below. In the engraving the 
bed-rock is not seen, being completely covered by the large boulders of quartz that have been 
excavated from the bank and washed. The bank is not attacked by pickaxe and shovel, but a 
powerful jet of water, delivered through the hose from the reservoir above, is thrown against 
its base. "The earth is soon washed away, and the overhanging mass of drift of earth and loose 
boulders falls to the ground. As rapidly as the finer portions are removed by the water, the 
loose stones and boulders are thrown back out of the way, while the smaller fragments, together 
with the sand, clay, and gold, are carried by the water into a long drain, or sluice-way, where 
the gold is collected. The operation is thus a continuous one, and the earth is not handled or 
transported except by the water. The only labor necessary is to remove the stones from the foot 
of the bluff as rapidly as they are washed. The whole operation may be more readily under- 
stood by the inspection of a sectional view of the claim, showing the bank of drift and the 
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IDEAL SECTION OF A MINING CLAIM, MICHIGAN CITY 
underlying bed-rock of slate. A space for the escape of the water and earth is also show? 
under the heap; of stones thrown back of the base of the bank; but the sluice-ways are p 
ally much larger, and in large claims are constructed at great cost, even by tunnelling through 
solid rock in order to secure the proper descent. The entrance or opening to the gluices 18 
secured by a grating of strong timbers, so that no large boulders can enter. à 
The operation of sluicing is another striking and important feature in the art of mining; " 
practised in California. Earth, gravel, and stones are washed by hundreds of tons in a ves 
space of time without being handled. The sluice is a long channel or race-way to conduct t : 
water or gravel, and is constructed either in the surface of the bed-rock by excavating, OT f" 
of boards. The former is known as the ground-sluice, and the latter as the board-sluice. 
