The sand and water were ejected from the vents with some force. A few observers estimated the height of the spouts at about 12 feet, but this probably refers to stray splashes. It is clear, however, that the sand and water were forced not only up to the surface, but even in a continuous stream to heights of from two to ten feet above it. In many districts, trunks of trees or lumps of coal and fossil resin were washed up with the water, and even, in one or two cases, pebbles of hard rock weighing as much as half-a-pound. The origin of the sand-vents is to be sought in the presence of a water-bearing bed situated not far below the surface. In the central area, where there was a marked vertical component in the motion, this bed during the earthquake was compressed between those above and below it, and the resulting pressure was in places sufficient to force the water and sand, through the fissures formed by the earthquake, up to and beyond the surface. The gradual settling of the upper layer, cut up by the fissures, into the underlying quicksand, prolonged the process for some time after the shock was over; and, when the pressure was at last relieved, some of the water was sucked back and so produced the crateriform hollows. _Rise of River-Beds, etc._--Over a large area, river-channels, tanks, wells, etc., were filled up, partly by the outpouring of the sand from vents, but chiefly, as shown by the forcing up of the central piers of bridges, by the elevation of the beds of the excavations. In the lowlands which lie between the Garo hills and the Brahmaputra, there were numerous channels from 15 to 20 feet in depth, the beds of which were pressed up until they became level with the banks, while a compensating subsidence took place close to the streams on either side. The general tendency of the earthquake was thus to obliterate the surface inequalities, so that, when the rivers rose later on, the district was extensively flooded. Besides these deferred floods, there occurred immediately after the earthquake a sudden rise in many rivers, amounting to from two to ten feet, followed by a gradual decline to the former state in two or three days. At Gauhati, for instance, the river-gauge showed that, at about three-quarters of an hour after the earthquake, the water stood 7 feet 7 inches higher than on the morning of June 12th; at 7 A.M. on June 13th it had fallen to 5 feet 8 inches, and at the same time on the two following days to 2 feet 7 inches and 6 inches, showing that the water had returned nearly to its original level after the lapse of two and a half days. In most of the large rivers, the rise of water was due to the formation of partial dams formed by the local elevation of the river-beds described above. As the barriers were composed of loose sand, they were gradually scoured away and the material was spread over the bottom so as to leave the water at a level slightly higher than that which it maintained before the earthquake.