Page:Popular Science Monthly Volume 69.djvu/85

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81
OUR GREATEST EARTHQUAKES

found. There are no roads, and for many miles not even a solitary settler is to be seen, but with a good horse and a guide familiar with the cracks, blows and 'sand slews' the region can be penetrated and the earthquake features examined. It is in the depths of these forests along the St. Francis river that the cracks reach their greatest development. How wide they may have been when first formed and

PSM V69 D085 Trees tilted by the new madrid earthquake.png

3. Trees Tilted by New Madrid Earthquake. (Photo by Fuller.)

how deep, no one can tell. The originally steep banks have crumbled and the fissures partly filled until at the present time they resemble a deep ditch more than a crack. Yet some of these ditch-like depressions are still thirty feet or more across and so deep that a man on horseback can not see over the top, even when he has succeeded in scrambling or sliding down the steep sides. From cracks of this size there are all gradations down to little ones of only a half a foot in depth, but all are still distinctly recognizable. Most of them are within a quarter or half a mile from some river and have a general north-south direction, as if the surface of the land shifted bodily towards the waterways, leaving great rents in the ground where the materials parted. One of the smaller of the cracks is shown by one of the illustrations of the present article (Fig. 1).

Fissures of another, but equally conspicuous type are the land-slide cracks formed where steep slopes, such as those along the east side of Reelfoot Lake in western Tennessee, occurred within the earthquake area. Here the bluffs, which are several hundred feet in height, were literally shaken to pieces by the shocks, the trees uprooted, overturned, or prostrated, and great masses of earth precipitated down the steep hillsides. Figure 2 shows some of the scarps thus formed, while another shows trees overturned at the same time (Fig. 3). Sometimes the original trunks are decayed and gone, all perhaps but a projecting stump, but shoots from the original have often taken their place as giants of the forest.

The features for which the New Madrid earthquake is most renowned, however, are the swamps and lakes which resulted from the warping of the surface. The former may be seen at many places in southern Missouri and northern Arkansas. In the view of such a