North America Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! === Geology === {{Main|Geology of North America}} ==== Geologic history ==== [[File:NorthAmerica-WaterDivides.png|thumb|The principal water divisions in [[Canada]], the [[United States]], and [[Mexico]]]] [[Laurentia]] is an ancient [[craton]] which forms the geologic core of North America; it formed between 1.5 and 1.0 billion years ago during the [[Proterozoic]] eon.<ref>{{Cite journal |last=Dalziel |first=I.W.D. |year=1992 |title=On the organization of American Plates in the Neoproterozoic and the breakout of Laurentia |journal=GSA Today |volume=2 |issue=11 |pages=237β241}}</ref> The [[Canadian Shield]] is the largest exposure of this craton. From the Late [[Paleozoic]] to Early [[Mesozoic]] eras, North America was joined with the other modern-day continents as part of the supercontinent [[Pangaea]], with [[Eurasia]] to its east. One of the results of the formation of Pangaea was the [[Appalachian Mountains]], which [[Taconic orogeny|formed]] some 480 mya, making it among the oldest mountain ranges in the world. When Pangaea began to rift around 200 mya, North America became part of [[Laurasia]], before it separated from Eurasia as its own continent during the mid-[[Cretaceous]] period.<ref name="ReferenceA">{{cite book|last1=Merali |first1=Zeeya |last2=Skinner |first2=Brian J. |title=Visualizing Earth Science |publisher=Wiley |isbn=978-0-470-41847-5|date=9 January 2009 }}{{page needed|date=February 2014}}</ref> The Rockies and other western mountain ranges began forming around this time from a period of mountain building called the [[Laramide orogeny]], between 80 and 55 mya. The formation of the [[Isthmus of Panama]] that connected the continent to South America arguably occurred approximately 12 to 15 mya,<ref name="Origins">{{cite web|url=http://www.livescience.com/50450-when-panama-land-bridge-appeared.html|title=Land Bridge Linking Americas Rose Earlier Than Thought|work=LiveScience.com|date=10 April 2015|access-date=3 October 2015|archive-date=4 October 2015|archive-url=https://web.archive.org/web/20151004171848/http://www.livescience.com/50450-when-panama-land-bridge-appeared.html|url-status=live}}</ref> and the [[Great Lakes]] (as well as many other northern freshwater lakes and rivers) were carved by receding glaciers about 10,000 years ago. North America is the source of much of what humanity knows about [[geologic time]] periods.<ref name="dinopedia-american"/> The geographic area that would later become the United States has been the source of more varieties of [[dinosaur]]s than any other modern country.<ref name="dinopedia-american"/> According to [[Paleontology|paleontologist]] Peter Dodson, this is primarily due to stratigraphy, climate and geography, human resources, and history.<ref name="dinopedia-american"/> Much of the Mesozoic Era is represented by exposed outcrops in the many arid regions of the continent.<ref name="dinopedia-american">{{cite book|last=Dodson |first=Peter |year=1997 |chapter=American Dinosaurs |title=Encyclopedia of Dinosaurs |editor1-last=Currie |editor1-first=Phillip J. |editor2-last=Padian |editor2-first=Kevin |publisher=Academic Press |pages=10β13}}</ref> The most significant [[Late Jurassic]] dinosaur-bearing fossil deposit in North America is the [[Morrison Formation]] of the western U.S.<ref name="jurassicdistribution">{{cite book|last=Weishampel |first=David B. |year=2004 |title=Dinosaur distribution (Late Jurassic, North America)|editor-last1=Weishampel |editor-first1=David B. |editor2-last=Dodson |editor2-first=Peter |editor3-last=Halszka |editor3-first=OsmΓ³lska |series=The Dinosauria |location=Berkeley |publisher=University of California Press |pages=543β545 |isbn=978-0-520-24209-8}}</ref> ==== Canada ==== {{Main|Canada}} [[File:USGS Geologic Map of North America.jpg|thumb|A geologic map of North America published by the [[U.S. Geographical Survey]]]] [[Canada]] is geographically one of the oldest regions in the world, with more than half of the region consisting of [[Precambrian]] rocks that have been above sea level since the beginning of the [[Palaeozoic]] era.<ref name="Marianopolis">{{cite book|last=Wallace |first=Stewart W. |url=http://faculty.marianopolis.edu/c.belanger/quebechistory/encyclopedia/GeologyofCanada.htm |title=Geology Of Canada |series=The Encyclopedia of Canada |volume=III |place=Toronto |publisher=University Associates of Canada |year=1948 |pages=23β26 |via=Marianopolis College |access-date=1 June 2011 |url-status=dead |archive-url=https://web.archive.org/web/20100704145706/http://faculty.marianopolis.edu/c.belanger/quebechistory/encyclopedia/GeologyofCanada.htm |archive-date=4 July 2010 }}</ref> Canada's mineral resources are diverse and extensive.<ref name="Marianopolis"/> Across the Canadian Shield and in the north there are large iron, nickel, [[zinc]], copper, gold, lead, [[molybdenum]], and [[uranium]] reserves. Large diamond concentrations have been recently developed in the Arctic,<ref>{{cite magazine |url=https://www.wired.com/science/planetearth/magazine/16-12/ff_diamonds_sb |title=Digging for Diamonds 24/7 Under Frozen Snap Lake |magazine=Wired |access-date=1 June 2011 |archive-date=3 September 2011 |archive-url=https://web.archive.org/web/20110903095743/http://www.wired.com/science/planetearth/magazine/16-12/ff_diamonds_sb |url-status=live }}</ref> making Canada one of the world's largest producers. Throughout the Shield, there are many mining towns extracting these minerals. The largest, and best known, is [[Greater Sudbury|Sudbury]], Ontario. Sudbury is an exception to the normal process of forming minerals in the Shield since there is significant evidence that the [[Sudbury Basin]] is an ancient [[meteorite]] [[impact crater]]. The nearby, but less-known [[Temagami Magnetic Anomaly]] has striking similarities to the Sudbury Basin. Its magnetic anomalies are very similar to the Sudbury Basin, and so it could be a second metal-rich impact crater.<ref name="GH">{{cite news|url=http://gdcinfo.agg.nrcan.gc.ca/app/3Dimaging/temagami_e.html |title=3-D Magnetic Imaging using Conjugate Gradients: Temagami anomaly |access-date=13 March 2008 |url-status=dead |archive-url=https://web.archive.org/web/20090711184237/http://gdcinfo.agg.nrcan.gc.ca/app/3Dimaging/temagami_e.html |archive-date=11 July 2009 }}</ref> The Shield is also covered by vast boreal forests that support an important logging industry. ==== United States ==== {{Main|United States}} The [[Contiguous United States|lower 48 U.S. states]] can be divided into roughly five [[physiographic]] provinces: # The [[American Cordillera|American cordillera]] # The [[Canadian Shield]]<ref name="Marianopolis"/> Northern portion of the upper [[Midwestern United States|midwestern U.S.]] # The stable platform # The [[coastal plain]] # The Appalachian [[orogeny|orogenic]] belt The geology of [[Alaska]] is typical of that of the cordillera, while the major islands of [[Hawaii]] consist of [[Neogene]] [[volcano|volcanics]] erupted over a [[hotspot (geology)|hot spot]]. {{multiple image | align = right | direction = horizontal | header = | header_align = left/right/center | header_background = | footer = | footer_background = | width = | image1 = North america terrain 2003 map.jpg | width1 = 180 | caption1 = A 2003 image of North America's [[bedrock]] and terrain | image2 = North america basement rocks.png | width2 = 180 | caption2 = A 2015 map of North America's [[craton]]s and basement rocks }} ==== Central America ==== {{Main|Central America}} [[File:Tectonic plates Caribbean.png|thumb|[[Central America]] rests on the [[Caribbean Plate]].]] [[Central America]] is geologically active with [[volcanic eruption]]s and earthquakes occurring from time to time. In 1976 Guatemala was hit by [[1976 Guatemala earthquake|a major earthquake]], killing 23,000 people; Managua, the capital of Nicaragua, was devastated by earthquakes in 1931 and 1972, the last one killing about 5,000 people; three earthquakes devastated El Salvador, one in 1986 and two in 2001; one [[2009 Costa Rica earthquake|earthquake]] devastated northern and central Costa Rica in 2009, killing at least 34 people; in [[2009 Honduras earthquake|Honduras]] a powerful earthquake killed seven people in 2009. Volcanic eruptions are common in the region. In 1968 the [[Arenal Volcano]], in Costa Rica, erupted and killed 87 people. Fertile soils from weathered volcanic lavas have made it possible to sustain dense populations in agriculturally productive highland areas. Central America has many [[mountain range]]s; the longest are the [[Sierra Madre de Chiapas]], the [[Cordillera Isabelia]], and the [[Cordillera de Talamanca]]. Between the mountain ranges lie fertile valleys that are suitable for the people; in fact, most of the population of Honduras, Costa Rica, and Guatemala live in valleys. Valleys are also suitable for the production of coffee, beans, and other crops. Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here. You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see Christianpedia:Copyrights for details). Do not submit copyrighted work without permission! Cancel Editing help (opens in new window) Discuss this page