It is a pun on the name of the Dutch artist M. C. Escher (the initials stand for Maurits Cornelis, but the full names are almost never used), who is famous for mathematically precise prints of surreal spaces that seem to fold into themselves or "go around" where nothing ought to go around.
For example, look at Waterfall or Möbius Strip II.
An esker is particular kind of elongated gravelly hill formed by material deposited in meltwater tunnels at the bottom of glaciers during the Ice Ages. Since it follows the path of a meltwater stream, it always goes from somewhere to somewhere. A circular one makes no geological sense and would need to have been made by a meltwater stream that went round and round without any source or outlet -- like the water in the channel of Waterfall.