Definition of "immemorial"

We will ride this morning to what we call the grove of Daphne. It is a real laurel grove. Some of the trees must be immemorial, and deserve to have been sacred, if once they were not so.

1870, B[enjamin] Disraeli, chapter XIV, in Lothair. […], volume III, London: Longmans, Green, and Co., page 148

...the fact of the immemorial taking of the toll, though it would be rightful in its origin if the spot was in a port, and wrongful if it was not in a port, did not of itself afford sufficient ground for inferring that the spot was an antient port, or that such special services were rendered, either by express stipulation in some lost grant, or by immemorial usage, as would support such a grant or custom.

1868, James Redfoord Bulwer, editor, The Law Reports. Court of Common Pleas., volume 3

Now, I still think that for this box of matches to have escaped the wear of time for immemorial years was a strange, and for me, a most fortunate thing.

1895 May 7, H[erbert] G[eorge] Wells, chapter X, in The Time Machine: An Invention, New York, N.Y.: Henry Holt and Company