Fig. 35. Crater of the Great Geyser of Iceland
It is a well-known fact that in geyser regions generally, the throwing of stones or other materials into the tube will frequently hasten an eruption. This is probably due to the fact that the throwing in of these things results in the raising of the water in the tube, thus hastening the eruption.
The New Zealand region is in the neighborhood of Lake Rotomahama in the northern island.
The geyser region in the Yellowstone Park is by far the most interesting of all geyser regions. This region is situated principally around Fire-Hole Fork of the Madison, and near Shoshone Lake at the head of Lake Fork of the Snake River. There are many geysers in this region, as well as simple hot springs. The temperature of their waters varies from between 160° and 200° F. to the boiling point of water at this elevation. As you are probably aware, water boils at the temperature of 212° F. only under the condition of the ordinary atmospheric pressure that exists at the level of the sea. At higher elevations, such as on the slopes of mountains, or on high plateaus, water boils at a lower temperature. The height of the country in which the Yellowstone Park is situated is so great that the water boils at temperatures of from 198° to 199° F.
The conical hillock of geyser cones from which the waters flow assume various shapes, two of which are shown in [Figs. 36] and [37].
