took part of the saturated material past the point where liquefaction occurred. This initially liquefied material began to move rapidly, releasing energy which liquefied the rest of the saturated portion of the tip, and almost instantaneously the nature of the saturated lower parts of Tip No. 7 was changed from that of a solid to that of a heavy liquid of a density of approximately twice that of water. This was 'the dark glistening wave' which several witnesses saw burst from the bottom of the tip.