Searching for coal is, not only at home but also abroad, a serious subject, and one in which the practical utility of connecting geological knowledge with active operations is particularly obvious, and which from actual experience I can well illustrate by many interesting cases which have come under my own notice. The first determinations in a coal “adventure” may be classified as follows:—

1. Where coal is not. 2. Where coal may be, but at too great a depth for working. 3. Where coal may be found convenient for working. 4. Its quality and extent.

In order to make what follows the more interesting, we may premise, what every Geologist now knows—that the earth is made up of strata of different kinds—e.g., sandstones, limestones, and argillaceous beds called rocks. The different strata have been formed step by step, layer upon layer. Each stratum has its distinct position and age in relation to other strata. The relative age and, consequently, position of a rock can be distinguished by mineral structure, fossil contents, or both.

Again, by way of still more clearly establishing our primary position, let the following table represent some of the strata above and below the general coal deposit:—

Now this partial table of British strata represents the coal measures as being overlaid by the New Red Sandstone deposits, and underlaid by the Mountain Limestone and Old Red Sandstone, which, though a general, is by no means the invariable rule in coal deposits, as sometimes the Mountain Limestone is absent, and the coal measures rest upon the old red system, as in great part of the Shropshire coal-field.