Mr. Croll, in an interesting paper, remarks that we do not err "in forming too great a conception of the length of geological periods," but in estimating them by years.
Croll jaunak, lan interesgarri batean, ohartarazten du, ez garela erratzen "aldi geologikoen luzeraren gehiegizko ideia eratzen dugulako", baizik urtez kalkulatzen ditugulako.