Underfall sb.

[UNDER-¹ 5 b.] A foot-hill slope.

1857.  Smith’s Dict. Grk. & Rom. Geog., II. 1274/2. The underfalls of the Alps that are thrust forward towards the plain.

1883.  Standard, 8 May, 4/8. The last ‘underfalls’ of the … plateau terminate to the North of Tonquin.