On gaining the outlet, where the channel of the Skaptar emerged into the plain, it might have been supposed that the burning flood would have at once spread over the low fields, which lay immediately before it, but, contrary to all expectations, this flow was for a time stopped by an immense unfathomed abyss in the river's bed, into which it emptied itself with great noise. When this chasm was at last filled, the lava increased by fresh flows, rose to a prodigious height, and breaking over the cooled mass, proceeded south towards the plain. In the meantime the thunder and lightning, together with subterranean roars, continued with little or no intermission. On the 18th of June, 1783, another dreadful eruption of red hot lava came from the volcano. This flowed with great velocity and force over the surface of the cooling stream that had been thrown out principally on the tenth of the month. Floating islands consisting of masses of flaming rock were seen on the surface of the lava stream, and the water that had been banked up on both sides of the stream was thrown into violent boiling. In the meantime people living along the Hverfisfloit, the next largest river to the east of the Skaptar, had not yet been visited by the lava streams. It is true that their vegetation had been destroyed by showers of red hot stone and ashes, and that both atmosphere and water were filled with poisonous substances. The land had also been plunged in utter darkness, so that it was scarcely possible at noonday to distinguish a sheet of white paper held up at the window from the blackness of the wall on either side. But the molten lava streams had not yet reached the people of this valley and they hoped that the eruption would soon be over, and that the lava flow would continue to follow the Skaptar. On the 3d of August, however, they were alarmed by seeing steam escaping from the River Hverfisfloit, and soon all its water was dried up, and a fresh lava flow poured down upon them. As in the case of the Skaptar, the melted rock completely filled the empty channel to the brink, and then overflowing, covered the low grounds on both sides, so that by the ninth of August it had reached the open and level country near its mouth and in the course of a few hours spread itself for a distance of nearly six miles across the plain. This flow continued after the end of August, and, indeed, even as late as the month of February, 1784, when a new eruption took place in this part of the country. Hecla, another well-known volcano in Iceland, situated about thirty miles from the southern coast, consists of three peaks, the central of which is the highest. Its craters form vast hollows on the sides of these peaks, and at the time of the eruption in 1766 were covered with snow. Hecla is believed to have been an active volcano long before Iceland was inhabited. No less than twenty-three eruptions have been recorded between A. D. 1004 and the great eruption of 1766-68.