a. Min. [f. TRAP sb.5 + -ean (L. -e-us + -AN): cf. marmorean.] Pertaining to, of the nature of, or consisting of trap-rock.
1813. Bakewell, Introd. Geol. (1815), 55. Domes of trappean porphyry.
1855. J. R. Leifchild, Cornwall Mines, 271. A very fertile soil is formed from what is geologically called ‘trappean ash,’ on the trap rocks.
1873. J. Geikie, Gt. Ice Age, xvi. 205. The trappean heights … between the valleys of the Clyde and the Irvine.
