undiggable

_ So I do sometimes -- and mair o 'ye than me, I jalouse; but I was gaun to ask ye if ye could imagine the delicht o' a fox gettin 'into an undiggable earth, just when the leadin' houn 'was at his hainches?

Heads and Tales : or, Anecdotes and Stories of Quadrupeds and Other Beasts, Chiefly Connected with Incidents in the Histories of More or Less Distinguished Men. Adam White 1848

I dislike both McCain and Palin, but poor journalism is undiggable.

Original Signal - Transmitting Buzz 2009

Tied at 25, Longhorns senior libero Savanna Gustafson served an undiggable ace into the Rams 'front court, then followed with another tough serve.

Glenwood Springs Post Independent - Top Stories 2008