No one has yet accounted for this remarkable phenomenon, and it remains a puzzle to the geological inquirer.
"The Desert Home" by Mayne Reid
I was not permitted to dwell long on the contemplation of this geological phenomenon.
"The Wild Huntress" by Mayne Reid
Wherever he goes he sees some insect, or shell, or plant, or flower, or forest-tree, or geological phenomenon worth noting.
"British Quarterly Review, American Edition, Volume LIV" by Various
Sampling at irregular intervals is sometimes imposed by the nature of the phenomenon being observed as in the case of geological measurement, anemometry or radar signals.
Random sampling in chirp space