Marathons

Are the marathons completely over?

i dont think so

Then when is the next one in lichess.org/?

idk

then how do you know they are still There?

Lichess organize marathons quarterly, so there is one in every season. Check it in the Tournament Winners page at the Marathon section:
lichess.org/tournament/leaderboard

Are there Classical or Rapid marathons on Lichess?

If I am not mistaken every Marathon was held so far consisted only fast Blitz games (3 to 8 minutes). Sadly, it is to quick for me. I prefer Classical.

Thanks