1811  (1897)  We drove briskly until sunrise, which found us at the bas fond where our horses wintered.
1877  . . . the sinuous trail . . . led across grassy bas-fonds under the shadow of the mountains. . . .
1897  Basfond is hardly a geographical name, being applicable to any piece of low land along a river or about a lake; it is used here in the same sense as we use bottom.