bas-relief
n
(a) [U] form of sculpture or carving in which a figure or design projects only slightly from its background (人像或图样略微凸出於平面的)半浮雕, 浅浮雕.
(b) [C] example of this 浅浮雕品.
and these will ply the short wings with such irresistible power that they can bore for long distances through an opposing gale before exhaustion follows.