A verb glossed “to beat flat” appearing in the Quenya Verbal System from 1948 (PE22/114). Tolkien designated it as a talat-stem verb, and it was thus derived from an (unattested) verbal root *ᴹ√PALAK. It may be a variant of ᴹQ. palpa- “to beat, batter” from The Etymologies of the 1930s that was based on the root ᴹ√PALAP (Ety/PALAP). It is possible that palka- replaces palpa- entirely, but I think the two can coexist with slightly different meanings.