[f. prec. + -IST.] One who explains certain phenomena in geology or physical geography by the action of existing streams.
1829. Proc. Geol. Soc., I. 145. He [W. D. Conybeare] first offers some introductory remarks on the opposite theories of the fluvialist and diluvialist, the former ascribing such denudations exclusively to the operation of the atmospherical waters falling on the districts.
