A dike is a barrier used to regulate or hold back water from a river, lake, or even the ocean. In geology, a dike is a large slab of rock that cuts through another type of rock. 4 – 12+ Earth Science, Geology, Engineering, Geography, Physical Geography. 4 Images.
What is a dike in geography?
A dike is a barrier used to regulate or hold back water from a river, lake, or even the ocean. In geology, a dike is a large slab of rock that cuts through another type of rock. 4 – 12+ Earth Science, Geology, Engineering, Geography, Physical Geography. 4 Images.
How is a dike formed?
When molten magma flows upward through near-vertical cracks (faults or joints) toward the surface and cools, dykes are formed. Dykes are sheet-like igneous intrusions that cut across any layers in the rock they intrude.
What is an example of a dike?
Ring dikes are intrusive igneous sheets that are circular, oval or arcuate in overall trend. … The Ossipee Mountains of New Hampshire and Pilanesberg Mountains of South Africa are two examples of ring dikes. In both of these instances, the minerals in the dike were harder than the rock that they intruded into.
What is the difference between a sill and a dike?
A sill is a concordant intrusive sheet, meaning that a sill does not cut across preexisting rock beds. … In contrast, a dike is a discordant intrusive sheet, which does cut across older rocks. Sills are fed by dikes, except in unusual locations where they form in nearly vertical beds attached directly to a magma source.
What’s the difference between a dike and a levee?
Levees protect land that is normally dry but that may be flooded when rain or melting snow raises the water level in a body of water, such as a river. Dikes protect land that would naturally be underwater most of the time.
What is dyke form of igneous rocks?
dike, also called dyke or geological dike, in geology, tabular or sheetlike igneous body that is often oriented vertically or steeply inclined to the bedding of preexisting intruded rocks; similar bodies oriented parallel to the bedding of the enclosing rocks are called sills.
What is the origin of gabbro?
Gabbro (/ˈɡæb. roʊ/) is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth’s surface. … Gabbro is also found as plutons associated with continental volcanism.
What is dyke wall?
A dyke is a thick wall that is built to stop water flooding onto very low-lying land from a river or from the sea. Synonyms: wall, barrier, dam, enclosure More Synonyms of dyke.
Why are sedimentary rocks called stratified rocks?
The sediments accumulate in different layers or strata arranged one above the other. Each layer or stratum has particles of given size. In sedimentary rocks each layer or stratum has particles of a given size. Therefore sedimentary rocks are also called stratified rocks.
What is the difference between a dyke and a ditch?
is that ditch is or ditch can be a trench; a long, shallow indentation, as for irrigation or drainage while dyke is or dyke can be (slang|pejorative) a lesbian, particularly one who appears macho or acts in a macho manner this word has been reclaimed, by some, as politically empowering (see usage notes).
How do sills form?
Sills: form when magma intrudes between the rock layers, forming a horizontal or gently-dipping sheet of igneous rock. The Whin Sill (top left image) in N. England provided a defensive cliff-line on which the Romans built Hadrian’s Wall.
What is a dike in a volcano?
Dikes are tabular or sheet-like bodies of magma that cut through and across the layering of adjacent rocks. … They form when magma rises into an existing fracture, or creates a new crack by forcing its way through existing rock, and then solidifies.
Is quartz an Aphanitic?
Aphanites are commonly porphyritic, having large crystals embedded in the fine groundmass, or matrix. … They consist essentially of very small crystals of minerals such as plagioclase feldspar, with hornblende or augite, and may contain also biotite, quartz, and orthoclase.
What is a levy dam?
Levee. (Dike) In hydrologic terms, a long, narrow embankment usually built to protect land from flooding. If built of concrete or masonary the structure is usually referred to as a flood wall. Levees and floodwalls confine streamflow within a specified area to prevent flooding.
Does New Orleans have levees?
The system can absorb a half-inch of rain an hour, or 12 inches in a day. That’s not enough to keep up with the rain-laden storms in New Orleans’ future. … Outside the perimeter levees, the rest of the New Orleans metropolitan region lacks the city’s level of protection. Levees are partial or non-existent.
What is water levy?
A levee is a natural or artificial wall that blocks water from going where we don’t want it to go. … The banks form levees made of sediment, silt, and other materials pushed aside by the flowing water. Levees are usually parallel to the way the river flows, so levees can help direct the flow of the river.
What is a mafic dyke?
Mafic dyke swarms are groups of vertical dykes with same orientation representing a system of pre-existing tensional crustal fracture swarms along which mafic magmas emplaced (Halls and Fahrin, 1987, Ernst et al., 1995, Hou et al., 2006). … Most of giant mafic dyke swarms were developed in Proterozoic time.
How do you identify gabbro?
Gabbro is a coarse-grained, dark-colored, intrusive igneous rock. It is usually black or dark green in color and composed mainly of the minerals plagioclase and augite. It is the most abundant rock in the deep oceanic crust.
Is gabbro a volcanic rock?
Gabbro is dark gray to greenish black color plutonic rock and chemically equivalent to volcanic basalt. The rock mainly contains Ca–plagioclase and ferromagnesian minerals such as pyroxene (augite and hypersthene or diallage) ± olivine.
What is the cleavage of gabbro?
This gabbro is roughly half pyroxene and half plagioclase. Pyroxene is typically duller and more blocky than hornblende, but most important are the cleavages intersecting at 90°.
What does dyke mean in Scotland?
In Scotland a dyke or dike is a stone wall, but in England a dyke is a ditch. In the Cumbrian dialect of English a Dike is the name given to a banked hedgerow.
Why do metamorphic rocks not have fossils?
Metamorphic rocks have been put under great pressure, heated, squashed or stretched, and fossils do not usually survive these extreme conditions.
Which rock is known as primary rock?
Igneous rocks are known as primary rocks as they are formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet’s mantle or crust. All other rocks are derived from them, so they are also called as parent rock.
What are secondary rocks?
Rocks composed of particles derived from the erosion or weathering of preexisting rocks, such as residual, chemical, or organic rocks formed of detrital, precipitated, or organically accumulated materials; specif., clastic sedimentary rocks.
What is another word for dike?
In this page you can discover 17 synonyms, antonyms, idiomatic expressions, and related words for dike, like: wall, embankment, causeway, levee, spillway, riverbed, barrier, dam, watercourse, batholith and butch.
What is a drainage ditch called?
Like a trench drain, a swale is a surface water drainage device. However, it’s a lot more subtle in terms of its appearance in the landscape. A swale is like a ditch but it’s broad and shallow, and usually covered or lined with turfgrass or other vegetation.
What are dikes in Holland?
Dikes are man-made structures that defend against natural forces like water, climate and altitude and are mostly constructed of material found on site. Over the centuries, the Netherlands had frequently been flooding, from the rivers as well as the sea in varying degrees and severity.
What are volcano rocks?
Volcanic rock (also called extrusive rock) is one type of magmatic rock (igneous rocks) and is the condensated product of extrusive magma after diagenesis and compaction, which differ greatly from sedimentary rocks in forming conditions, environments, and distribution.
What is a Laccolith in geology?
laccolith, in geology, any of a type of igneous intrusion that has split apart two strata, resulting in a domelike structure; the floor of the structure is usually horizontal. … Acidic rocks are more common than basic rocks in laccoliths.
What is Asill?
sill, also called sheet, flat intrusion of igneous rock that forms between preexisting layers of rock. Sills occur in parallel to the bedding of the other rocks that enclose them, and, though they may have vertical to horizontal orientations, nearly horizontal sills are the most common.
What is the difference between a dike and a sill quizlet?
What is the difference between a dike and a sill? Dikes are formed across vertical cracks, and sills are formed across horizontal ones.
Is obsidian an aphanitic?
The individual crystals in an aphanitic igneous rock are not distinguishable to the naked eye. Examples of aphanitic igneous rock include basalt, andesite and rhyolite. … The result is a natural amorphous glass with few or no crystals. Examples include obsidian.
Does obsidian exist?
obsidian, igneous rock occurring as a natural glass formed by the rapid cooling of viscous lava from volcanoes. Obsidian is extremely rich in silica (about 65 to 80 percent), is low in water, and has a chemical composition similar to rhyolite. Obsidian has a glassy lustre and is slightly harder than window glass.
Is obsidian porphyritic?
OBSIDIAN, a glassy volcanic rock of acid composition. … Few obsidians are entirely vitreous; usually they have small crystals of felspar, quartz, biotite or iron oxides, and when these are numerous the rock is called a porphyritic obsidian (or hyalo-liparite).