_Cracks and fissures formed in the ground._—Almost all large earthquakes have produced cracks in the ground. The cracks which were found in the ground at Yokohama (February 22, 1880) were about two or three inches wide, and from twenty to forty yards in length. They could be best seen as lines along a road running near the upper edge of some cliffs which overlook the sea at that place. The reason that cracks should have occurred in such a position rather than in others was probably owing to the greater motion at such a place, due to the face of the cliff being unsupported, and there being no resistance opposed to its forward motion. It often happens that earthquake cracks are many feet in width. At the Calabrian earthquake of 1783, one or two of the crevasses which were formed were more than 100 feet in width and 200 feet in depth. Their lengths varied from half a mile to a mile.[37] Besides these large cracks, many smaller ones of one or two feet in breadth and of great length were formed. In the large fissures many houses were engulfed. Subsequent excavations showed that by the closing of the fissures these had been jammed together to form one compact mass. These cracks are usually more or less parallel, and at the same time parallel to some topographical feature, like a range of mountains. For example, the cracks which were formed by the Mississippi earthquake of 1812 ran from north-east to south-west parallel to the Alleghanies. By succeeding shocks these crevasses are sometimes closed and sometimes opened still wider. Their permanency will also depend upon the nature of the materials in which they are made. During an earthquake large cracks may suddenly open and shut. During the convulsions of 1692 which destroyed Port Royal, it is said that many of the fissures which were formed, opened and shut. In some of these, people were entirely swallowed up and buried. In others they were trapped by the middle, and even by the neck, where if not killed instantaneously they perished slowly. Subsequently their projecting parts formed food for dogs.[38] The earthquake which, July 18, 1880, shook the Philippines caused many fissures to be found, which in some places were so numerous that the ground was broken up into steps. Near to the village of San Antonio the soil was so disturbed that the surface of a field of sugar-canes was so altered that in some cases the top of one row of full grown plants was on a level with the roots of the next. Into one such fissure a boat disappeared, and into another, a child. Subsequently the child was excavated, and its body, which was found a short distance below the surface, was completely crushed.[39] At the time of the Riobamba earthquake, not only were men engulfed, but animals, like mules, also sank into the fissures which were formed.