ed the next age, when coal was formed.

The rocks that bear the record of these living things in their fossils,
form strata of great thickness that overlie the Silurian deposits. There
is no break between them. So we understand that the sea changed its
shore-line only when the Silurian deposits rose to the water-level.

The Devonian sea was smaller than the Silurian. A great tract of
Devonian deposits occupies the lower half of the state of New York,
Canada between Lakes Erie and Huron, and the northern portions of
Indiana and Illinois. These older layers of the stratified rock are
covered with the deposits of later periods. Rivers that cut deep
channels reveal the earlier rocks as outcrops along their canyon walk.
The record of the age of fishes is, for the most part, still an unopened
book. The pages are sealed, waiting for the geologist with his hammer to
disclose the mysteries.

KING COAL

In this country, and in this age, who can doubt that coal is king? It is
one of the few necessities of life. In various sections of the country,
layers of coal have been discovered--some near the surface, others deep
underground. These are the storehouses of fuel which the coal miners dig
out and bring to the surface, and the railroads distribute. From
Pennsylvania and Ohio to Alabama stretches the richest coal-basin.
Illinois and Indiana contain another. From Iowa southward to Texas
another broad basin lies. Central Michigan and Nova Scotia each has
isolated coal-basins. All these have been discovered and mined, for they
lie in the oldest part of the country.

In the West, coal-beds have been discovered in several states, but many
regions have not yet been explored. Vast coal-fields, still untouched,
have been located in Alaska. The Government is trying to save this fuel
supply for coming generations. Many of the richest coal-beds from Nova
Scotia southward dip under the ocean. They have been robbed by the
erosive action of waves and running water. Glaciers have ground away
their substance, and given it to the sea. Much that remains intact must
be left by miners on account of the difficulties of getting out coal
from tilted and contorted strata.

As a rule, the first-formed coal is the best. The Western coal-fields
belong to the period following the Carboniferous Age. Although
conditions were favourable to abundant coal formation, Western coal is
not equal to the older, Eastern coal. It is often called _lignite_, a