The Lakes of California

The forms of the lands are determined in the main by the slow interaction of two antagonistic processes. One process, of interior origin and unsolved explanation, slowly deforms the earth's crust and makes its surface uneven. Associated with this deforming process in being of interior origin and of difficult explanation, but apparently acting independently of it, are volcanic eruptions which build up cones and domes and pour out lava flows of smaller or larger extent.