659. If the fluid mass be large, this polarization will then require considerable time to penetrate throughout it.
660. The polarizing process will issue from a definite point, which is different from water, and thus form the point upon which the light operates with greatest force.
661. This is solid ground. During the calcareous precipitation, there was no other ground present save that of the mountain tops. It was thus from these that the calcareous precipitation set out.
662. With each precipitation a greater number of mountain tops made their appearance, because the water sank; for the calcareous earth is about three times denser than water.
663. Such being the conditions belonging to the sedimentary periods, several consecutive centuries characterized by precipitations with repeated recessions and elevations of the water, elapsed and have left evidence of the time thus consumed.
664. The recession of the water was not always an ebbing or sinking in, but a diminution or disappearance of the same, like the water in a glass lessens in quantity, or becomes thoroughly solid, if salt crystallizes therein.
665. By such precipitations whole basins of land became dry or freed from sea-water. Streams therefore of fresh water originated, and with them corresponding organizations.
666. These streams gradually filled the basins and formed seas. As the seas coalesced by the constantly descending water, an inland sea arose.
667. This inland sea became again salidified, and that indeed of itself by the influence of light and the dissolution of the salt-banks, which were not overflown. Such is still the Caspian sea and others of that kind. In these marine plants and animals could again originate.
668. Thereupon new precipitations of salt succeeded, the gypsum and calx being again dissolved, and consequently diminutions also of water, whereby rivers again originated. One and the same basin of land was alternately covered with fresh and saline water.