loess (n.)

1833 (in Lyell), "unstratified deposit of loam," a special use from 1823 by German mineralogist Karl Cäsar von Leonhard (1779-1862) of German Löss "yellowish-gray soil," of a type found in the Rhine valley, from Swiss German lösch (adj.) "loose" (compare German los, from Proto-Germanic *lausaz, from PIE root *leu- "to loosen, divide, cut apart." Related: Loessial.