The history of this tremendous chasm is not hard to read. Ages ago this whole region was the basin of an immense lake. Then it became a centre of volcanic activity; vast quantities of lava was erupted, which, cooling under water, took the form of basalt; volumes of volcanic ash and rock-fragments were thrown out from the craters from time to time, forming breccia as it sunk through the water and mingled with the deposits from silicious springs. Over this were spread the later deposits from the waters of the old lake. In time the country was slowly elevated, and the lake was drained away. The easily eroded breccia along the river channel was cut out deeper and deeper as the ages passed, while springs and creeks and the falling rain combined to carve the sides of the cañon into the fantastic forms they now present, by wearing away the softer rock, and leaving the hard basalt and the firmer hot-spring deposits standing in massive columns and Gothic pinnacles. The basis material of the old hot spring deposits in silica, originally white as snow, are now stained by mineral waters with every shade of red and yellow--from scarlet to rose color, from bright sulphur to the daintiest tint of cream. When the light falls favorably on these blended tints the Grand Cañon presents a more enchanting and bewildering variety of forms and colors than human artist ever conceived. The erosion was practically arrested at the upper end of the cañon by a sudden transition from the softer breccia to hard basalt, and the falls are the result. From below the Upper Fall the vertical wall of basalt can be clearly seen passing diagonally across the rim. The Lower Fall was formed in the same way.