o big. There's millions of tons of rock pressing
down on a mine roof. Judging by the way you talk, Anton, I don't
believe you understand what a coal formation is, yet."

"Isn't it like Otto said, then?"

"Only in a way. Otto's description of the coal forests was near
enough--in spite of his ideas about goblins and sprites--and he was
correct in saying that the forests decayed under water and turned
into coal after they were pressed down by rock. But it wasn't the
Flood that did that, at least not the Flood that Otto was speaking of.
The coal forests existed millions of years before Noah.

"What's more, it wasn't only just once that the forests were covered
by a deluge. That happened several times, a hundred or more, in some
places.

"For centuries at a time, these gloomy and steaming forests grew in
boggy land, only a few inches above the level of the sea. Gradually
the land sank, the sea came in, the trees fell and decayed under the
water, and a layer of mud or sand was deposited over them. Then
gradually the land rose again just above the level of the sea, and a
new forest grew. Once more the land sank below the water, the second
forest fell into decay and upon that layer a new deposit of mud or
sand was laid. That gave two layers or seams of coal-forest-bog, to be
turned later into coal by pressure; and two layers or strata of mud or
sand, to be turned into shale and slate or into sandstone, also by
pressure.

"When a long time elapsed between the swampings, several centuries of
coal forests had made a deep bed of bog, which, ages after, became a
thick seam of coal. When the swampings happened close together, the
layer of bog was shallow, producing a thin seam of coal. In the same
way, the layers of shale or sandstone are thick or thin according to
the length of time that the land was under the water.

"Because of that, Anton, in nearly every colliery there is not just
one layer or seam of coal, but a number of them. There are sixteen
different seams in this mine, showing that the land rose and fell
sixteen times, probably in the course of a million years.

"Some mines show much bigger changes. In the famous coal basin of
Mons, in Belgium, there are 157 layers of coal, of which 120 are thick
enough to be workable. The Saar basin, on the left bank of the Rhine,
which has played so important a part in the international troubles
following the end of the World War, has 164 seams, with 77 of them
workable, giving