1864  (1962)  Some strike the bed-rock pitchin' in, / And some the bed-rock canna win. . . .
1962  Where bed rock is deep and requires deep holes to be sunk, the ordinary prospector is not prepared in the summer to get to bed rock on account of water.
2an. in get down to bed-rock, impoverished circumstances.
1889  (1892)  When the sombre shades of poverty have entered his old shack, he has in the miner's phraseology, got down to bed-rock or hard-pan. . . .
2bn. in get down to bed-rock, simple, basic principles; fundamentals.
1923  . . . there seemed no way of simplifying things, of getting down to bed-rock. . . .