Chapter IV.
WAS SUCH A CATASTROPHE POSSIBLE?
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| coal-measures of Pennsylvania. |
All that is needed to answer this question is to briefly refer to some of the facts revealed by the study of geology.
In the first place, the earth's surface is a record of successive risings and fallings of the land. The accompanying picture represents a section of the anthracite coal-measures of Pennsylvania. Each of the coal deposits here shown, indicated by the black lines, was created when the land had risen sufficiently above the sea to maintain vegetation; each of the strata of rock, many of them hundreds of feet in thickness, was deposited under water. Here we have twenty-three different changes of the level of the land during the formation of 2000 feet of rock and coal; and these changes took place over vast areas, embracing thousands of square miles.
All the continents which now exist were, it is well understood, once under water, and the rocks of which they are composed were deposited beneath the water; more than this, most of the rocks so deposited were the detritus or washings of other continents, which then stood
