le. A good many mountains
show the result of this, and if you look at such rocks as are sticking
up out of the ground you will see some of them standing right on edge.
Once in a while, part of the broken crust slid over the other part.
Then, too, though the surface may not always show it, there have been
breaks in the strata below, and at the break, the layer has sunk or
risen quite a distance from its former level.

"If that happens to a coal seam, you can see that where the seam
breaks, suddenly, the rest of it will continue on another level,
perhaps only a few feet higher or lower, perhaps a good deal more.
It's up to the mine geologist to find where the coal has gone to, and
it's the business of the mine engineer to remodel the entire system of
working the mine in order to get at that seam."

"And are all coal mines mixed up in that funny way?" Anton queried.

"Most of them. Oh, there's no end to the tricks a coal seam can play.
A deep coal seam may split into two narrow ones, too thin to work.
The whole seam may quickly dwindle away to nothing, showing that, in
ages past, a river came rolling over it and washed away all the forest
bog. Sometimes, especially with the lowermost seams, the forest grew
on rolling land, so that the bottom of the coal seam is irregular,
causing all sorts of trouble in laying rails for the cars to roll on.
Sometimes the layer of rock under a coal seam is so soft that when you
start to timber it, the timbers sink into the floor and the roof comes
toppling down.

"Among the queerest of all the things a mine geologist strikes are
what are called dykes. These are great shafts of igneous rock, which
were thrust up from the interior of the earth in a white-hot state and
which burned away the coal as they rose. They put a dead stop to a
working. I could tell you a dozen more freak things that a coal seam
can do. A mine geologist has not only a new problem to tackle with
every mine, but, often, with every mine gallery."

"Is that what you're studying to be, Clem?"

"No, indeed!" The young fellow's answer was emphatic. "That's 'way out
of my reach. It takes a college man, with special technical training
and a big experience, to be anything of a mine geologist. All I'm
trying to do is to learn enough about it so that when I get to be a
mine boss--if I ever do--I'll know what my chiefs are trying to do and
I'll be able to help them.

"Take Otto, for example. There isn't a better worker in th