The Collaborative International Dictionary of English v.0.48:

Outcrop \Out*crop"\, v. i. (Geol.)
   To come out to the surface of the ground; -- said of strata.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Outcrop \Out"crop`\, n. (Geol.)
   (a) The coming out of a stratum to the surface of the ground.
       --Lyell.
   (b) That part of inclined strata which appears at the
       surface; basset.
       [1913 Webster]

WordNet (r) 3.0 (2006):

outcrop
    n 1: the part of a rock formation that appears above the surface
         of the surrounding land [syn: outcrop, outcropping,
         rock outcrop]
    v 1: appear on the surface, come to the surface on the ground;
         "Big boulders outcropped"

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "outcrop":
   appear, arise, become manifest, become visible, come, come forth,
   come forward, come in sight, come out, come to hand, come to light,
   crop out, discernibleness, emerge, enter, epiphany, exposure,
   fade in, heave in sight, issue, issue forth, look forth, loom,
   manifestation, materialize, observability, outcropping, peep out,
   perceptibility, rear its head, revelation, rise, see the light,
   seeableness, show, show up, stream forth, strike the eye, the seen,
   the visible, turn up, visibility, visibleness, visuality,
   what is revealed