e marshy
lowlands with lakes of fresh or brackish water came into existence.
There were such marshes in the areas that are now covered by New
Mexico, Colorado, Wyoming, Dakota, and Montana. Westward for some
distance the land was higher, but in the states of Washington,
Oregon, and California there were other marshy lowlands covered
with heavy vegetation.

We know from what we have seen of the manner in which wood decays,
that in the dry, open air it does not accumulate, but is in great
part carried away by the wind. It is only in swamps and shallow
bodies of water that the decaying wood can gather in beds. From
these facts we have a right to draw conclusions as to the former
nature of the surface where there are no coal-beds. There are extensive
beds of limestone in the western United States which are of the
same age as the coal-beds in the east. As such beds of limestone
could have formed only in the ocean, their presence throws a good
deal of light upon the geography of those distant times.

Upon the Pacific slope the marshes were not so extensive, nor did
they last for so long a period, as those in the East. Nature seems
to have confined her strongest efforts at coal-making to the country
east of the Rocky Mountains. Perhaps she thought that the people
of the West would not need coal if she gave them plenty of gold
and silver.

In the Appalachian mountains Nature folded the strata and left
them in such a position that the coal could be mined easily. In
the Mississippi Valley the beds were left flat, almost in their
original position, so that shafts had to be sunk to reach the coal.
Upon the Pacific slope Nature seems to have had a large amount
of trouble in arranging things satisfactorily. She has made and
remade the mountains so many times, and folded and broken the crust
of the earth so severely where the swamps stood, that now large
portions of the coal beds which once existed have crumbled and
been washed away by the streams. The scanty supply of coal which
now remains is in most places hard to find and difficult to mine.

[Illustration: FIG. 108.--SEAMS OF COAL ENCLOSED IN SANDSTONE,
CALIFORNIA]

The best coal mined near the Pacific comes from Vancouver Island.
Large beds of a younger and poorer coal are found southeast of
Puget Sound. There are other beds in the Coast ranges of western
Oregon, and a few small ones in the Coast ranges of California.
The great interior region between the Rocky Mountains