of the Sierra Nevada, from five hundred to seven thousand feet
above the level of the sea. They are all gold-yielding, and therefore
they have been sought and examined. They have yielded probably _three
hundred millions_ in all; they now produce perhaps eight million dollars
annually. They are not less interesting to the miner than to the
geologist, not less important to the statesman than to the antiquarian."

At the risk of being considered tedious by some of my boy-readers, I
will transcribe the writer's explanation of the existence of these dead
rivers. For the reason we must go back to a remote geological epoch:
"The main cause must have been the subsequent rise of the Sierra Nevada.
Suppose that a range of mountains, seven thousand feet high, were
upheaved thirty miles east of the Mississippi; that the bed of that
stream were on the mountain side, three thousand feet above the sea, and
that thirty miles west the country maintained its present level; the
result would be that the present Mississippi would soon be a dead river;
it would be cut across by streams running down the mountain side, and
flowing into a new Mississippi, thirty miles or more west of the present
one. We know that the Sierra Nevada has been upheaved; that a large
stream ran on what is now the mountain side, and that it has been
succeeded by a new river farther west, and we must infer that the death
of the old and the birth of the new river were caused by the upheaval."

Reference is here made to the Big Blue Lead, the largest dead river
known in California, which has been traced for a distance of sixty-five
miles, from Little Grizzly, in Sierra County, to Forest Hill, in Placer
County. The original river, however, is thought to have run for many
hundreds of miles. Eventually traces of its existence may be found
elsewhere.

It is not to be supposed that Tom and his friends knew anything about
dead rivers, or troubled themselves as to how the rich deposits had been
made, or how long they had been waiting discovery. They were chiefly
engaged with more practical considerations. They found a rich harvest in
the ravines, and they went to work energetically.

The work was monotonous, and a detailed account of their progress would
be tiresome. What we chiefly care about is results, and these may be
gathered from a conversation which took place some five months later.

Under a tent, at night-fall, reclined the three friends. They looked
contented, an