The geology of the Appalachians dates back more than 1.1 billion years to the Mesoproterozoic era when two continental cratons collided to form the supercontinent Rodinia, 500 million years prior to the later development of the range during the formation of the supercontinent Pangea. The rocks exposed in today's Appalachian Mountains reveal elongate belts of folded and thrust faulted marine sedimentary rocks, volcanic rocks and slivers of ancient ocean floor – strong evidence that these rocks were deformed during plate collision. The birth of the Appalachian ranges marks the first of several mountain building plate collisions that culminated in the construction of the supercontinent Pangea with the Appalachians and neighboring Anti-Atlas mountains near the center. These mountain ranges likely once reached elevations similar to those of the Alps and the Rocky Mountains before they were eroded.
The Acadian orogeny is a long-lasting mountain building event which began in the Middle Devonian, reaching a climax in the early Late Devonian. It was active for approximately 50 million years, beginning roughly around 375 million years ago, with deformational, plutonic, and metamorphic events extending into the Early Mississippian. The Acadian orogeny is the third of the four orogenies that formed the Appalachian orogen and subsequent basin. The preceding orogenies consisted of the Potomac and Taconic orogeny, which followed a rift/drift stage in the Late Neoproterozoic. The Acadian orogeny involved the collision of a series of Avalonian continental fragments with the Laurasian continent. Geographically, the Acadian orogeny extended from the Canadian Maritime provinces migrating in a southwesterly direction toward Alabama. However, the Northern Appalachian region, from New England northeastward into Gaspé region of Canada, was the most greatly affected region by the collision.
The Taconic orogeny was a mountain building period that ended 440 million years ago and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the East coast of the United States. As the mountain chain eroded in the Silurian and Devonian periods, sediments from the mountain chain spread throughout the present-day Appalachians and midcontinental North America.
The Geology of Pennsylvania consists of six distinct physiographic provinces, three of which are subdivided into different sections. Each province has its own economic advantages and geologic hazards and plays an important role in shaping everyday life in the state. From the southeast corner to the northwest corner of the state, the include: the Atlantic Plain Province province, the Piedmont Province, the New England Province, the Ridge and Valley Province, the Appalachain Province, and the Central Lowlands Province.
The geology of the Iberian Peninsula consists of the study of the rock formations on the Iberian Peninsula, which includes Spain, Portugal, Andorra, and Gibraltar. The peninsula contains rocks from every geological period from the Ediacaran to the Quaternary, and many types of rock are represented. World-class mineral deposits are also found there.
West Virginia's geologic history stretches back into the Precambrian, and includes several periods of mountain building and erosion. At times, much of what is now West Virginia was covered by swamps, marshlands, and shallow seas, accounting for the wide variety of sedimentary rocks found in the state, as well as its wealth of coal and natural gas deposits. West Virginia has had no active volcanism for hundreds of millions of years, and does not experience large earthquakes, although smaller tremors are associated with the Rome Trough, which passes through the western part of the state.
Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, although originally it also included the cratonic areas of Greenland and also the northwestern part of Scotland, known as the Hebridean Terrane. During other times in its past, Laurentia has been part of larger continents and supercontinents and itself consists of many smaller terranes assembled on a network of Early Proterozoic orogenic belts. Small microcontinents and oceanic islands collided with and sutured onto the ever-growing Laurentia, and together formed the stable Precambrian craton seen today.
The geology of Massachusetts includes numerous units of volcanic, intrusive igneous, metamorphic and sedimentary rocks formed within the last 1.2 billion years. The oldest formations are gneiss rocks in the Berkshires, which were metamorphosed from older rocks during the Proterozoic Grenville orogeny as the proto-North American continent Laurentia collided against proto-South America. Throughout the Paleozoic, overlapping the rapid diversification of multi-cellular life, a series of six island arcs collided with the Laurentian continental margin. Also termed continental terranes, these sections of continental rock typically formed offshore or onshore of the proto-African continent Gondwana and in many cases had experienced volcanic events and faulting before joining the Laurentian continent. These sequential collisions metamorphosed new rocks from sediments, created uplands and faults and resulted in widespread volcanic activity. Simultaneously, the collisions raised the Appalachian Mountains to the height of the current day Himalayas.
The geology of North America is a subject of regional geology and covers the North American continent, the third-largest in the world. Geologic units and processes are investigated on a large scale to reach a synthesized picture of the geological development of the continent.
The geology of Somaliland is very closely related to the geology of Somalia. Somaliland is a de facto independent country within the boundaries that the international community recognizes as Somalia. Because it encompasses the former territory of British Somaliland, the region is historically better researched than former Italian Somaliland. Somaliland is built on more than 700 million year old igneous and metamorphic crystalline basement rock.. These ancient units are covered in thick layers of sedimentary rock formed in the last 200 million years and influenced by the rifting apart of the Somali Plate and the Arabian Plate.
The geology of Virginia began to form 1.8 billion years ago and potentially even earlier. The oldest rocks in the state were metamorphosed during the Grenville orogeny, a mountain building event beginning 1.2 billion years ago in the Proterozoic, which obscured older rocks. Throughout the Proterozoic and Paleozoic, Virginia experienced igneous intrusions, carbonate and sandstone deposition, and a series of other mountain building events which defined the terrain of the inland parts of the state. The closing of the Iapetus Ocean, to form the supercontinent Pangaea added additional small landmasses, some of which are now hidden beneath thick Atlantic Coastal Plain sediments. The region subsequently experienced the rifting open of the Atlantic Ocean in the Mesozoic, the development of the Coastal Plain, isolated volcanism and a series of marine transgressions that flooded much of the area. Virginia has extensive coal, deposits of oil and natural gas, as well as deposits of other minerals and metals, including vermiculite, kyanite and uranium.
The geology of Ohio formed beginning more than one billion years ago in the Proterozoic eon of the Precambrian. The igneous and metamorphic crystalline basement rock is poorly understood except through deep boreholes and does not outcrop at the surface. The basement rock is divided between the Grenville Province and Superior Province. When the Grenville Province crust collided with Proto-North America, it launched the Grenville orogeny, a major mountain building event. The Grenville mountains eroded, filling in rift basins and Ohio was flooded and periodically exposed as dry land throughout the Paleozoic. In addition to marine carbonates such as limestone and dolomite, large deposits of shale and sandstone formed as subsequent mountain building events such as the Taconic orogeny and Acadian orogeny led to additional sediment deposition. Ohio transitioned to dryland conditions in the Pennsylvanian, forming large coal swamps and the region has been dryland ever since. Until the Pleistocene glaciations erased these features, the landscape was cut with deep stream valleys, which scoured away hundreds of meters of rock leaving little trace of geologic history in the Mesozoic and Cenozoic.
The geology of Arizona began to form in the Precambrian. Igneous and metamorphic crystalline basement rock may have been much older, but was overwritten during the Yavapai and Mazatzal orogenies in the Proterozoic. The Grenville orogeny to the east caused Arizona to fill with sediments, shedding into a shallow sea. Limestone formed in the sea was metamorphosed by mafic intrusions. The Great Unconformity is a famous gap in the stratigraphic record, as Arizona experienced 900 million years of terrestrial conditions, except in isolated basins. The region oscillated between terrestrial and shallow ocean conditions during the Paleozoic as multi-cellular life became common and three major orogenies to the east shed sediments before North America became part of the supercontinent Pangaea. The breakup of Pangaea was accompanied by the subduction of the Farallon Plate, which drove volcanism during the Nevadan orogeny and the Sevier orogeny in the Mesozoic, which covered much of Arizona in volcanic debris and sediments. The Mid-Tertiary ignimbrite flare-up created smaller mountain ranges with extensive ash and lava in the Cenozoic, followed by the sinking of the Farallon slab in the mantle throughout the past 14 million years, which has created the Basin and Range Province. Arizona has extensive mineralization in veins, due to hydrothermal fluids and is notable for copper-gold porphyry, lead, zinc, rare minerals formed from copper enrichment and evaporites among other resources.
The geology of Austria consists of Precambrian rocks and minerals together with younger marine sedimentary rocks uplifted by the Alpine orogeny.
The bedrock of Colorado was assembled from island arcs accreted onto the edge of the ancient Wyoming Craton. The Sonoma orogeny uplifted the ancestral Rocky Mountains in parallel with the diversification of multicellular life. Shallow seas covered the regions, followed by the uplift current Rocky Mountains and intense volcanic activity. Colorado has thick sedimentary sequences with oil, gas and coal deposits, as well as base metals and other minerals.
The geology of North Carolina includes ancient Proterozoic rocks belonging to the Grenville Province in the Blue Ridge. The region experienced igneous activity and the addition of new terranes and orogeny mountain building events throughout the Paleozoic, followed by the rifting of the Atlantic Ocean and the deposition of thick sediments in the Coastal Plain and offshore waters.
The geology of Kyrgyzstan began to form during the Proterozoic. The country has experienced long-running uplift events, forming the Tian Shan mountains and large, sediment filled basins.
The geology of Newfoundland and Labrador includes basement rocks formed as part of the Grenville Province in the west and Labrador and the Avalonian microcontinent in the east. Extensive tectonic changes, metamorphism and volcanic activity have formed the region throughout Earth history.
The geology of Yukon includes sections of ancient Precambrian Proterozoic rock from the western edge of the proto-North American continent Laurentia, with several different island arc terranes added through the Paleozoic, Mesozoic and Cenozoic, driving volcanism, pluton formation and sedimentation.
The geology of the Norwegian Sea began to form 60 million years ago in the early Cenozoic, as rifting led to the eruption of mafic oceanic crust, separating Scandinavia and Greenland. Together with the North Sea the Norwegian Sea has become highly researched since the 1960s with the discovery of oil and natural gas in thick offshore sediments on top of the Norwegian continental shelf.
