Decimillennium

According to this teaching believed in by Aristotle if we may credit Censorinus—the “great year” consists of 21,000 odd years (the latter varying) or six Chaldean saros consisting of 3,500 years each. These two decimillenniums are naturally halved, the first period of 10,500 years bringing us to the top of the cycle and a minor cataclysm; the latter decimillennium to a terrible and universal geological convulsion.

Source: wiktionary

These two principles are to some extent in conflict in every animal group and at all times; sometimes the one preponderates so that for millions of years the species remains the same, again the other preponderates so that perhaps even in a few decimillennia new subspecies arise.

Source: wiktionary

Occult philosophy teaches that the displacement of ocean beds takes place every decimillennium.

Source: wiktionary