669. Marine and fresh-water animals could therefore originate and perish alternately. And this is the explanation of the fact why banks inclosing both kinds of animals are found above and below each other.
670. An alternating ingress of the sea is not therefore necessary in all cases to explain the occurrence of marine fossil remains. Such an assumption is also wholly inconceivable. Nor is alternating elevation and depression of the soil necessary to the explanation of this phenomenon.
671. During the time of precipitation the temperature of the water and consequently of the earth and air also was necessarily raised. All creatures, which then originated, must correspond therefore to those of warmer climates.
672. The fossil remains do not require the assumption of a change having taken place in the inclination or bearing of the earth's axis; nor of a heating of the surface by a fiery interior.
673. With every later precipitation other animals and plants must originate, because the temperature and also the mixture of water was changed. The fossils therefore indicate the age of the sedimentary strata.
674. During the last precipitations the creatures of colder climates must have originated.
675. Land animals cannot, or but rarely, be found in the sedimentary strata, if even they had already been in existence prior to their formation. For the inundations did not break in suddenly, but the water rose by degrees. They had time therefore to retire to the high grounds.
676. Land plants may, on the contrary, lie in the sedimentary strata, because of their inability to escape.
677. The bones of birds and men must be found least of all fossilized, because a retreat by them was most easily effected. It does not follow, from our not finding them, that they have not existed.
678. The different fossil remains have therefore not simply lived, where they are found, but originated there also. Some of course may have been floated also to these localities.