However wisely the configuration, elevation and slope of the land may now seem to be adapted for the reception of water from the air, for the subterranean channels of the springs that well up between the diverse layers of earth (suitable for various products) and for the course of the rivers, yet a closer investigation of them shows that they have resulted simply as the effect partly of volcanic eruptions, partly of ﬂoods, or even of invasions of the ocean.