But greater fissures than these have been formed by earthquakes, especially those of the class created by a slipping of the earth's strata. In the case of an earthquake on the South Island of New Zealand, in 1848, a fissure having an average width of eighteen inches could be clearly seen extending in a direction parallel to the mountain chain for a distance of sixty miles, and during a later earthquake in the same region, in 1855, a fracture was formed that could be clearly traced for a distance of nearly ninety miles. In some cases these fissures or fractured parts of the crust are left with one of their sides at a higher level than the opposite side. This was the case of the great Japanese earthquake of October 28th, 1891. There are three kinds of waves produced by earthquakes; namely, the earthquake waves proper through the earth; the sound waves in the air, and great forced waves in the sea. The sound waves of course reach the air from the point of origin below the earth's surface through the solid materials of the crust, and take on the curious varieties already described in connection with the sounds accompanying earthquakes. We have already briefly described the manner in which the earthquake waves travel through the materials of the earth's crust. There remain to be discussed the great waves that are rolled up in the ocean during an earthquake shock. These waves are, perhaps, among the most destructive phenomena of great earthquakes. The following are only some of the more remarkable of such waves, and have been taken from Mallet's collection of earthquake data. During some of the great earthquakes on the coasts of Chile and Peru, huge waves from the ocean did great damage when they reached the land. In the earthquake of 1590, ocean waves rushed for several leagues inland over the coast of Chile, carrying with them ships that were left high and dry as the wave receded. In the earthquake of 1687, Callao was inundated by a great wave from the Pacific Ocean, and ships were carried a full league into the country. During the earthquake of 1746, Callao was again swept away by a huge ocean wave. At later times earthquake waves have caused great damage to several other parts of the coast of South America. Ocean waves of this character are formed by successive upward and downward movements at the bottom of the ocean, following each other at very brief intervals. Le Conte points out that the sudden upheaval of the bed of the ocean forms a huge mound in the surface of the water which results in a large wave that spreads rapidly in all directions. Waves produced in this manner sometimes reach a height of fifty to sixty feet. They are not readily observed in the deep ocean, but as soon as they reach the shallow waters near the shore they rush forward, forming waves from fifty to sixty feet in height and, rushing over the land, sweep everything before them.