Page:The fairy tales of science.djvu/352

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306
PLUTO'S KINGDOM.

regions, but also in places presenting, with the exception of hot wells and mineral springs, no traces of volcanic activity within historical periods.

Among extinct volcanoes those of central France have attracted most attention. In the districts of Auvergne, Velay, and the Vivarais, there are seen several hundred volcano-shaped conical hills, with more or less perfectly-formed craters on their tops. These conical hills are called in the language of the country "Puys" which means mountain peaks. They are all of them dome-shaped, varying in height from 500 feet to 2800 feet above the level of the plain from which they rise in an irregular chain, thirty miles in length and two miles in breadth; the plain itself, some forty-five miles long and twenty miles wide, is 1200 feet above the level of the sea.

All the cones are formed of volcanic materials, such as lava, sand, and cinders; and in many of them are found well-defined craters. The highest of these is called "Puy de Dome" It is 4000 feet above the level of the sea; it is composed entirely of volcanic materials, and has a regular crater, measuring fifteen hundred feet round, and three hundred feet deep.

On the top of another of these remarkable cones, called the "Puy de Pariou," there is a very deep extinct crater, a mile round, which is now closed in, and covered with turf and grass. From the lower part of this conical hill a stream of lava has