Editing Geology of the Appalachians (section)

=== Crystalline Appalachians ===
[[File:Mid-Atlantic Appalachian rock types.gif|thumb|upright=2|Geological map of the southern Crystalline Appalachians]]
The Blue Ridge, Piedmont, Adirondack, and New England Provinces are collectively known as the Crystalline Appalachians because they consist of Precambrian and Cambrian igneous and metamorphic rocks.<ref name="nyc">{{cite web |title=The Sedimentary Appalachians |work=NYC Regional Geology |url=http://3dparks.wr.usgs.gov/nyc/valleyandridge/sedimentaryapp.htm |archive-url=https://web.archive.org/web/20110516070439/http://3dparks.wr.usgs.gov/nyc/valleyandridge/sedimentaryapp.htm |archive-date=May 16, 2011 |access-date=May 20, 2010 |url-status=dead }}</ref>

The Blue Ridge Thrust Belt Province underlies parts of eight states from central Alabama to southern Pennsylvania. Along its western margin, the Blue Ridge is thrust over the folded and faulted margin of the Appalachian basin, so that a broad segment of [[Paleozoic]] strata extends eastward for tens of miles, buried beneath these subhorizontal crystalline thrust sheets.<ref>{{cite journal|last1=Harris|first1=L.D.|last2=Harris|first2=A.G.|last3=de Witt, Jr.|first3=W.|last4=Bayer|first4=K.C.|year=1981|title=Evaluation of the southern eastern overthrust belt beneath Blue Ridge-Piedmont thrust|journal=American Association of Petroleum Geologists Bulletin|volume=65|issue=12|pages=2497–2505|doi=10.1306/03b599ef-16d1-11d7-8645000102c1865d}}</ref> At the surface, the Blue Ridge consists of a mountainous to hilly region, the main component of which are the Blue Ridge Mountains that extend from Georgia to Pennsylvania. Surface rocks consist mainly of a core of moderate-to high-rank crystalline metamorphic or igneous rocks which, because of their superior resistance to weathering and erosion, commonly rise above the adjacent areas of low-grade metamorphic and sedimentary rock. The province is bounded on the north and west by the Paleozoic strata of the Appalachian Basin and on the south by Cretaceous and younger sedimentary rocks of the [[Gulf Coastal Plain]]. It is bounded on the east by metamorphic and sedimentary rocks of the [[Piedmont (United States)|Piedmont Province]].<ref name="otherProv">{{USGS|title=Blue Ridge Thrust Belt (068), Piedmont Province (069), Atlantic Coastal Plain Province (070), Adirondack Province (071), and New England Province (072)|url=http://certmapper.cr.usgs.gov/data/noga95/prov71/text/prov71.pdf|author=Robert C. Milici}}</ref>

The Adirondack and New England Provinces include sedimentary, meta-sedimentary, and [[Intrusive rock|plutonic]] igneous rocks, mainly of Cambrian and Ordovician age, similar [[lithologically]] to rocks in the Blue Ridge and Piedmont Provinces to the south. The uplifted, nearly-circular Adirondack Mountains consist of a core of ancient Precambrian rocks that are surrounded by upturned Cambrian and Ordovician sedimentary rocks.<ref name="otherProv" />