ivide, would run into the Columbia, and they could see the Rockies,
just on ahead to the west. As Billy has said, the Indian girl always was
telling them that her people lived along in here. An obsidian arrow
meant nothing to them. But it meant much to later explorers to the south
of here."

"It's a good specimen he's got," said Billy, looking it over. "The
Indians liked to work obsidian; it would cleave so sharp and clean. I
thought they had them all picked up, long ago. Up in the Shoshoni Cove
they found a good many, first and last. All this was their hunting
ground. A little over the Divide it gets awfully rough, and not much
game."

They spent some time around the Rock, examining it, finding the cliff to
be about one hundred and fifty feet in height and giving a good view out
over the valley plains, over which one could see many miles, and from
which the great rock itself could be seen for great distances.

"Here was the old ford of the road agents' trail," said Billy. "They
crossed here and headed out, east and south, for the hills between here
and Virginia City. They were hunting for easier money than beaver then,
though--gold! This was the murderers' highway, right by here. Over a
hundred men were murdered on this hundred miles."

They went back to their encampment and, after their simple preparations
were over for the evening, spread out their books and maps once more,
John endeavoring laboriously to fill in the gaps of his own map; rather
hard to do, since they had not followed the actual stream course on
their way up with the pack train.

"This Wisdom River, now," said he, "must have been a puzzler, sure
enough. That's called the Big Hole to-day. I'll bet she was a beaver
water, too, as well as full of trout. Wonder if she had any grayling in
her. Here's a town down below here, near the mouth of the Red Rock,
called Grayling."

"Must have been grayling in all these upper Missouri waters," nodded
Billy. "I don't think the _Journal_ mentions them, but they saw
whitefish, and the two often go together, though by no means always. The
Madison is a grayling stream, or was--the South Fork's good now, and so
is Grayling Creek, or was. The headwaters of the Red Rock were full of
grayling once. The trouble is, so many motor cars now, that everybody
gets in, and they soon fish a stream out."

"Shall we get to see a grayling?" asked Rob. "You know, we got the
Arctic grayling on the Bell River, in the Arctic region