overdeepen
/ˌəʊvəˈdiːp(ə)n/Chiefly Physical Geography
verb
1 [with object] To erode (a valley) more deeply by glacial action than would occur by water erosion alone.
2 [with object] More generally: to deepen excessively or abnormally; especially to further deepen by erosion.
Origin
Early 20th century; earliest use found in Science. From over- + deepen, probably after overdeepening.