Sep`tu*a*ges"i*mal\, a. Consisting of seventy days, years, etc.; reckoned by seventies. Our abridged and septuagesimal age. --Sir T. Browne.
Here is an improvised fan fiction sentence:
After the "Dude*" took a toke from the empyreal weed from the gods, he finally came down from his heavenly septuagesimal year high.