It has recently been visited by Lieutenant Somerville, of the British Navy. Some time or other a volcanic vent opened at the bottom of the ocean, and the lava that poured out of it piled up higher and higher, until it finally overtopped the sea. A great volcanic mountain had been formed, and the part of it that came into view above the waste of waters was, of course, an island. As time went on this volcano was the scene of one of those tremendous explosions that sometimes tear mountains to pieces. It was such a cataclysm that blew off the upper 3,000 feet of Krakatoa some years ago. The explosion at Niuafou had a remarkable result. The interior of the crater was blown out to a considerable depth, leaving only the narrow rim, in this case a nearly perfect ring, around the deep central cavity. Such is the island of to-day. A thousand Tongans live in the five villages that lie along the outer slope of that crater wall. The drainage from the inner slope has partly filled the cavity, forming a lake whose waters, though slightly alkaline, are drinkable. From the top of the crater rim one looks down upon the peaceful lake within, with its three little islands and the curiously shaped peninsula jutting out into it; and outside the rim is the ever-restless ocean. WHERE THE VALLEY WAS A HILL IS. _From the Chicago Record._ SEATTLE, Wash., April 6.--A tremendous upheaval, accompanied by wonderful changes, occurred in the Mount Baker district March 27. What had once been a valley and the bed of a river is now a hill seventy feet high. The noise of the upheaval was heard at Hamilton, ten miles away. A report of the occurrence was brought to the city by D. P. Simons, Jr. Simons says the noise of the upheaval sounded like heavy thunder. He and his party, who were examining timber lands, journeyed in the direction from which the sound came, and were astonished to see a huge mound of earth, nearly a quarter of a mile square, where formerly there had been a valley. In places the mound was seventy feet high. The Nooksachk River had been turned from its course, and ran around one side of a hill. Nearly in the center of this high bank of earth was a large lake. A forest had formerly occupied the ground, and trees which had escaped destruction rose above the water. There were cracks here and there in the mound large enough to ingulf a horse and wagon. There was a smell of sulphur in the air, and it is Mr. Simons’s impression that the disturbance was caused by gases underneath the mountain. William Hadley, a trapper, whose wrecked cabin now stands in the center of the huge mound, was absent at the time of the upheaval, and thus escaped death. His cabin was split in two. REMARKABLE GEOLOGICAL DISCOVERY.