The ashes of the volcanoes are sometimes carried to vast distances by the air currents—_e.g._, from the western coast of South America to the Antilles; from Iceland to Norway and Sweden; from Vesuvius (1906) to Holstein. Best known in this respect is the eruption of the Krakatoa, which drove the fine ashes up to an elevation of 30 km. (18 miles). The finest particles of these ashes were slowly carried by the winds to all parts of the earth, where they caused, during the following two years, the magnificent sunrises and sunsets which were spoken of as “the red glows.” This glow was also observed in Europe after the eruption of Mont Pelée. The dust of Krakatoa further supplied the material for the so-called “luminous clouds of the night,” which were seen in the years 1883 to 1892 floating at an elevation of about 80 km. (50 miles), and hence illuminated by the light of the sun long after sunset. The crater of Kilauea, on the high volcano of Mauna Loa, in Hawaii—this volcano is about of the same height as Mont Blanc—has excited special interest. The crater forms a large lake of lava having an area of about 12 sq. km. (nearly 5 sq. miles), which, however, varies considerably with time. The lava boiling at red glow is constantly emitting masses of gas under slight explosions, spurting out fiery fountains to a height of 20 m. (65 ft.) into the air. Here and there lava flows out from crevices in the wall of the crater down the slope of the mountain, until the surface of the lake of lava has descended below these cracks. As a rule, this lava is of a thin fluid consistency, and it spreads, therefore, rather uniformly over large areas. Of a similar kind are also the floods of lava which are sometimes poured over thousands of square kilometres on Iceland. The so-called Laki eruption of the year 1783 was of a specially grand nature. Though occurring in an uninhabited district, it did a great amount of damage. In the more ancient geological periods, especially in the Tertiary age, similar sheets of lava of vast extensions have been spread over England and Scotland (more than 100,000 sq. km., roughly, 40,000 sq. miles); over Deccan, in India, 400,000 sq. kms. (150,000 sq. miles), up to heights of 2000 m. (6500 ft.); and over Wyoming, Yellowstone Park, Nevada, Utah, Oregon, and other districts of the United States, as well as over British Columbia. [Illustration: Fig. 4.—Photograph of Vesuvius, 1906. Chiefly clouds of ashes] In other cases the slowly ejected lava is charged with large volumes of gases, which escape when the lava congeals and burst it up into rough, unequal blocks, forming the so-called block lava (Fig. 5). The streams of lava can likewise produce terrible devastation when they descend into inhabited districts; on account of their slow motion, they rarely cause loss of life, however.