but that this element, which has played such a large part in his development and civilization, was here before him, waiting, like so many other things in nature, to be his servant and friend.  As Vulcan was everywhere rampant during this age, throwing out enough lava in India alone to put a lava blanket four or five feet thick over the whole surface of the globe, it was probably this fire that charred the wood.  It would be interesting to know if these enormous lava-flows always followed the subsidence of some part of the earth’s crust.  In Cretaceous times both the subsidence and the lava-flows seem to have been worldwide.

IV

We seem to think that the earth has sown all her wild oats, that her riotous youth is far behind her, and that she is now passing into a serene old age.  Had we lived during any of the great periods of the past, we might have had the same impression, so tranquil, for the most part, has been the earth’s history, so slow and rhythmical have been the beats of the great clock of time.  We see this in the homogeneity of the stratified rocks, layer upon layer for thousands of feet as uniform in texture and quality as the goods a modern factory turns out, every yard of it like every other yard.  No hitch or break anywhere.  The bedding-planes of many kinds of rock occur at as regular intervals as if they had been determined by some kind of machinery.  Here, on the formation where I live, there are alternate layers of slate and sandstone, three or four inches thick, for thousands of feet in extent; they succeed each other as regularly as the bricks and mortar in a brick wall, and are quite as homogeneous.  What does this mean but that for an incalculable period the processes of erosion and deposition went on as tranquilly as a summer day?  There was no strike among the workmen, and no change in the plan of the building, or in the material.

The Silurian limestone, the old red sandstone, the Hamilton flag, the Oneida conglomerate, where I have known them, are as homogeneous as a snowbank, or as the ice on a mountain lake; grain upon grain, all from the same source in each case, and sifted and sorted by the same agents, and the finished product as uniform in color and quality as the output of some great mill.

Then, after a vast interval, there comes a break:  something like an end and a new beginning, as if one day of creation were finished and a new one begun.  The different formations lie unconformably upon each other, which means revolution of some sort.  There has been a strike or a riot in the great mill, or it has lain idle for a long period, and when it has resumed, a different product is the result.  Something happened between each two layers.  What?