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Anoutcrop orrocky outcrop is a visible exposure ofbedrock or ancientsuperficial deposits on the surface of the Earth and otherterrestrial planets.[1]
In most places, bedrock or superficial deposits are covered bysoil and vegetation. Where these are removed througherosion,tectonic uplift, or excavation by humans, the underlying rock maycrop out, or be exposed. Most frequently, this occurs on steep hillsides, mountain ridges and mountaintops, river banks, and areas which are tectonically active. For example,Finland has many coastal andlittoral outcrops due toglacial erosion during the last glacial maximum (c. 11000 BC), followed by scouring by sea waves, thenisostatic uplift.
Outcrops allow direct observation and sampling of thebedrockin situ forgeologic analysis and creatinggeological maps. In situ measurements are critical for proper analysis ofgeological history and outcrops are therefore extremely important for understanding thegeologic time scale of earth history. Some of the types of information that cannot be obtained except from bedrock outcrops or by precise drilling and coring operations, arestructural geology features orientations (e.g. bedding planes,fold axes,foliation), depositional features orientations (e.g. paleo-current directions, grading,facies changes),paleomagnetic orientations. Outcrops are also very important for understanding fossil assemblages, and paleo-environment, and evolution as they provide a record of relative changes within geologicstrata.
Accurate description, mapping, and sampling for laboratory analysis of outcrops made possible all of the geologic sciences and the development of fundamental geologic laws such as thelaw of superposition, theprinciple of original horizontality,principle of lateral continuity, and theprinciple of faunal succession.
Outcrops occur in numerous forms, including, but not limited to:[2]
OnOrdnance Survey maps inGreat Britain, cliffs are distinguished from outcrops: cliffs have a continuous line along the top edge with lines protruding down; outcrops have a continuous line around each area of bare rock. An outcrop example inCalifornia is theVasquez Rocks, familiar fromlocation shooting use in manyfilms, composed of upliftedsandstone.[3][4]Yana is another example of outcrops, located inUttara Kannada district inKarnataka,India.
The dictionary definition ofoutcrop at Wiktionary
