It is important to note that it was in the eighteenth century that
this first happened - well before Darwin was born. The pioneer
geologist James Hutton, for instance, wrote that he could see 'no
vestige of a beginning' to the earth's history - and he died in
1797.
I think that your general point is correct, but one has to be a bit
careful with this line from Hutton. Hutton accepted a steady-state
view, according to which constructive (e.g. volcanoes) and destructive
(e.g. erosion) processes made local and (geologically relatively) short
term changes, but averaged out overall. Thus, observing the process at
any point gave no more indication of ultimate age than would observing a
planet orbiting would give any indication of how long it had been
orbiting. Hutton did accept a longer period for earth history than
nearly any of his contemporaries (his private estimates went up, I
believe, to around a quarter of a million years), but the "no vestige of
a beginning" remark, if I understand the situation correctly, bore more
on the steady state aspect of his views than on the increased age aspect
of his views. I think.
Del