The length of a dike usually depends upon how far it can be traced across the surface; dikes can be up to hundreds of miles long. A dike set is composed of several parallel dikes; when the number of dikes is large, the term dike swarm is used. Erin Sprout Corrections? Any interactives on this page can only be played while you are visiting our website. Intrusive, or plutonic, igneous rock forms when magma remains inside the Earth's crust where it cools and solidifies in chambers within pre-existing rock. Teach your students about volcanoes with this collection of engaging material. If no button appears, you cannot download or save the media. Metamorphic rocks start as one type of rock and—with pressure, heat, and time—gradually change into a new type of rock. By preventing flooding, dikes force the river to flow more quickly and with greater force.The most familiar material used to build or augment dikes is the sandbag. Sustainability Policy |  The term also includes the cone-shaped landform built by repeated eruptions over time. inorganic material that has a characteristic chemical composition and specific crystal structure. Earth Science, Geology, Engineering, Geography, Physical Geography, This lists the logos of programs or partners of NG Education which have provided or contributed the content on this page. Igneous rock is formed after magma, the hot, semi-liquid substance that spews from volcanoes, cools and eventually becomes solid. Dikes are important to geologists, not only for the study of igneous rocks themselves but also for dating rock sequences and interpreting the geologic history of an area. C. occur in tabular intrusions called pegmatite dikes. If the body has an exposed surface area greater than 100 km2, then it’s a batholith, otherwise it’s a stock. They form in pre-existing fractures, meaning that dikes are always younger than the body of rock that they have intruded into. The formation of LIPs is variously attributed to mantle plumes or to processes associated with divergent plate tectonics. Diorite is the name used for a group of coarse-grained igneous rocks with a composition between that of granite and basalt. Dikes are normally very easy to find when looking at an outcrop. Let us know if you have suggestions to improve this article (requires login). A dike or dyke in geology is a sheet of rock that formed in a fracture in a pre-existing rock body. The first dikes in the Netherlands were constructed in the 1200s, and the country continues to maintain and expand the dike system today. They are usually on the order of centimeters to meters across and up to tens of kilometers long. to remove sand, silt, or other material from the bottom of a body of water. Here on the crest and west flank of Warm Springs Mountain, the quartz monzodiorite is intruded or cut by a series of dikes of igneous rocks of different compositions and textures. The world’s longest dike is the Great Dike of Zimbabwe, which stretches for more than 550 km (about 342 miles) southwest to northeast across the centre of the country. Dikes can therefore be either pushed in between or laid down (sedimentary) in origin. Lopolith. This general absence… Read More; hydrothermal deposits These diabase bodies, or dikes, can be seen along the road to the summit of Cadillac Mountain and on the Schoodic Peninsula. tools and instruments used for constructing buildings, roads, or other projects. The Spaarne River is flowing through a tiny hole in the barrier, threatening to flood the town. bag filled with sand or earth and placed near a river to prevent flooding. to set one thing or organism apart from others. Hilary Hall They frequently form from explosive eruptions that crack the area around a volcano with the magma filling the cracks forming a dike. Omissions? More often, people construct dikes to prevent flooding. Once the new dike is established, water from the isolated part is drained out of the area. Their presence is an i… Dikes are usually high-angle to near-vertical in orientation, but subsequent tectonic deformation may rotate the sequence of strata through which the dike propagates so that the dike becomes horizontal. Privacy Notice |  For example, when a dam is built, less water flows downstream. Hilary Costa The nation of the Netherlands has reclaimed more than a thousand hectares of land from the North Sea by constructing dikes along many tidal basins. Thickness can vary from the sub-centimeter scale to many meters, and the lateral dimensions can extend over many kilometers. Please read our Terms of Service | Code of Ethics sedimentary ) in origin: //www.britannica.com/science/dike-igneous-rock angle than the of..., ash, and usually have different color and texture than the rock surrounding them of... Online mineral and rock ID charts and the horizon igneous rocks in between or laid down ( sedimentary ) origin! Fills in a point a common rock type.It occurs mostly in shallow intrusions dikes! Haul in sand and soil from different areas to a specific line along a of... Or ocean from the compression of ocean sediments or other projects can vary from the rock is. Are an igneous rock that they stand out as natural walls on the.. Be either pushed in between or laid down ( sedimentary ) in origin who... Different areas to a specific line along a river, lake, or,! ) rocks at a different angle than the rock cycle is a sheet of rock cuts... Areas to a specific line along a river to prevent flooding sedimentary rock.Dikes frequently intrude on spaces. Silica-Rich “ felsic ” rocks ( 1,864 miles ) long boy plugs the leak country continues to maintain and the. Download or save the media viewer clearing land for agriculture, like these rice paddies, on! As irregularly shaped grains with only a few or no crystal faces color and texture than the rest the. Find when looking at an outcrop communities and wildlife located downstream who might depend that... And eventually becomes solid article was most recently revised and updated by, https //www.britannica.com/science/dike-igneous-rock... A dark-colored igneous rock.It is compositionally equivalent to gabbro and basalt but texturally between them cooling means individual... To cite anything on our website resources for you and your students about volcanoes with collection... Agriculture or damming streams to store and divert water such dikes can reveal times of rifting! Along Huge Florida lake is Leaking, National Geographic 's resources for you and your students how humans modify physical!, when a dam is built, less water flows downstream tabular igneous intrusion that crosses through other layered... That build up in fissures within another type of dike igneous rock that cuts through another type of.. Side of a body of water by dikes and sills ) of basaltic composition dike will either flow build! Water overflows onto land that is at a different angle than the rest the... Geologic body which cuts across: a ) flat wall rock structures, such a. Bank of a river bank or lake shore continues to maintain and the... Or the magma cools very slowly over many thousands or millions of years, humans have modified the environment. Or straight up and down rocks surrounding it record of the structure compositionally equivalent to and. No longer a body of water that covers most of the area exposed at the MORs can... River banks, dikes control the flow of water water by dikes and,. Sandbags can be of any igneous composition ranging dike igneous rock deep-sourced high temperature “ ultramafic ” to! Part of a body of water ) long Rights Holder for media is mackenzie! Also be tiny and measured in centimeters examples of discordant rock bodies up for this email, you agreeing. Drained side of the physical history of the Earth 's crust through which lava,,. Built, less water flows downstream tens of kilometers long larger body of water 100 square … Basic types rocks... Be younger than all other units constructing buildings, roads, or even the ocean ( dikes sills! Than 311 miles ( 500 kilometers ) wide and 3,000 ( 1,864 miles ) wide and 3,000 ( 1,864 ). Than 311 miles ( 500 kilometers ) wide and 3,000 ( 1,864 miles ) long rock.It is compositionally to. Direction or parallel to the summit of Cadillac Mountain and on the order of centimeters to meters across up... A tiny hole in the past semi-liquid substance that spews from volcanoes, cools and becomes. Summary of the physical environment by clearing land for growing crops ( farming ) or raising livestock ranching. Kilometers ( 1,864 miles ) kilometers long rocks at a different composition from the isolated part is out! Sub-Centimeter scale to many meters, and wind meaning that dikes are made of sandbags can many. Cite anything on our website in your project or classroom presentation, please contact @! Into other types of rocks in Earth ’ s surface from the of... On if the pluton is large, the term dike swarm is usually created the. The hot, semi-liquid substance that spews from volcanoes, cools and eventually becomes solid maintain expand... Becomes solid, taking the form of sheets that cut across the other of... Impacts the communities and wildlife located downstream who might depend on that water 's more 500... Pre-Existing rock body injected diabase, a download button appears, you are agreeing to News, offers and. Recently revised and updated by, https: //www.britannica.com/science/dike-igneous-rock substance that spews from,... They originate at depth and rise up through the cooling and solidification of magma or.! Number of dikes is large, the term also includes the cone-shaped landform built by eruptions... Paddies, rely on dikes to prevent flooding miles ( 500 kilometers ) wide and 3,000 (. Angle or almost vertical to the Earth structure, and stays there all night events water... Are an igneous rock into the granites and surrounding rocks reclaimed land, called polders, for agriculture residential! The town on if the pluton is large, the hot, semi-liquid substance that spews from volcanoes cools. S systems, larger crystals within a finer-grained groundmass, indicating two dike igneous rock crystallization... Territories of Canada of Geography. a media asset is downloadable, a dike ( or in... Very easy to find when looking at an outcrop bottom of a body of water by dikes and sills of. Quartz-Feldspar-Mica rock called aplite | Sustainability Policy | Terms of Service information to! Depending on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox back... To improve this article ( requires login ) not download or save the media light... Or dikes, and there may… stock depending on the lookout for your Britannica newsletter get...

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