A chimney of lava is called a _dike_. In mountainous countries dikes are common. Sometimes small, they may also be hundreds of feet across, often standing high above the softer strata, which rains have worn away. Dikes often look like ruined walls, and may be traced for miles where they have been overturned in the mountain-making process. The great lava flood of the Northwest happened when the Coast Range was born. Along the border of the Pacific Ocean vast sedimentary deposits had accumulated during the Cretaceous and Tertiary Periods. Then the mighty upheaval came, the mountain ridge rose at the end of the Miocene epoch and stretched itself for hundreds of miles through the region which is now the coast of California and Oregon. Great fissures opened in the folded crust, and floods of lava overspread an area of 150,000 square miles. A dozen dead craters show to-day where those immense volcanic chimneys were. The depth of the lava-beds is well shown where the Columbia River has worn its channel through. Walls of lava three thousand feet in thickness rise on each side of the river. They are made of columns of basalt, fitted together, like cells of a honeycomb, and jointed, forming stone blocks laid one upon another. The lava shrinks on cooling and forms prisms. In Ireland, the Giants' Causeway is a famous example of basaltic formation. In Oregon, the walls of the Des Chutes River show thirty lava layers, each made of vertical basalt columns. The palisades of the Hudson, Mt. Tom, and Mt. Holyoke are examples on the eastern side of the continent of basaltic rocks made by lava floods. Northern California, northwestern Nevada, and large part of Idaho, Montana, Oregon, and Washington are included in the basin filled with lava at the time of the great overflow, which extended far into British Columbia. It is probable that certain chimneys continued to discharge until comparatively recent times. Mt. Rainier, Mt. Shasta, and Mt. Hood are among dead volcanoes. Quite a different history has the great Deccan lava-field of India, which covers a larger area than the basin of our Northwest, and is in places more than a mile in depth. It has no volcanoes, nor signs of any ever having existed. The floods alone overspread the region, which shows no puny "follow-up system" of scattered craters, intermittently in eruption. THE FIRST LIVING THINGS