metaconglomerate foliated metaconglomerate foliated

The zone in the photomicrograph outlined with the red dashed line is different from the rest of the rock. In contrast, nonfoliated metamorphic rocks do not contain minerals that align during metamorphism and do not appear layered. Foliations typically bend or curve into a shear, which provides the same information, if it is of a scale which can be observed. 2011 Richard Harwood | profharwood@icloud.com | Home. Drag the appropriate labels to their respective targets. Marble is metamorphosed limestone. [http://commons.wikimedia.org/wiki/ File:Migmatite_in_Geopark_on_Albertov.JPG] Most gneiss has little or no mica because it forms at temperatures higher than those under which micas are stable. What are the two textures of metamorphic rocks. A special type of metamorphism takes place under these very high-pressure but relatively low-temperature conditions, producing an amphibole mineral known as glaucophane (Na2(Mg3Al2)Si8O22(OH)2). The rock in the upper left of Figure 10.9 is foliated, and the microscopic structure of the same type of foliated rock is shown in the photograph beneath it. Rocks that form from regional metamorphism are likely to be foliated because of the strong directional pressure of converging plates. There are two main types of metamorphism: There are two types of textures on metamorphic rocks: Think of foliated rocks as something that is foiled. Non-foliated textures have minerals that are not aligned. The protolith for slate is shale, and sometimes fossils that were present in the original rock can be seen in freshly sheared layers of slate. Physical Geology, First University of Saskatchewan Edition by Karla Panchuk is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted. In contrast, nonfoliated metamorphic rocks do not contain minerals that align during metamorphism and do not appear layered. An example of contact metamorphism, where magma changes the type of rock over time, Metamorphism of slate, but under greater heat and pressure thane slate, Often derived from metamorphism of claystone or shale; metamorphosed under more heat and pressure than phyllite, Metamorphism of various different rocks. Determination of this information is not easily accomplished in this lab. Shocked quartz (Figure 6.32 left) refers to quartz crystals that display damage in the form of parallel lines throughout a crystal. Phyllite is similar to slate, but has typically been heated to a higher temperature; the micas have grown larger and are visible as a sheen on the surface. Adding foil creates a layer, so foliated rocks are layered rocks. More technically, foliation is any penetrative planar fabric present in metamorphic rocks. Foliation. Metamorphic rocks are those that begin as some other kind of rock, whether it's igneous, sedimentary or another metamorphic rock. Following such a methodology allows eventual correlations in style, metamorphic grade, and intensity throughout a region, relationship to faults, shears, structures and mineral assemblages. Each mineral has a specific chemical composition and a characteristic crystalline structure. Figure 10.24 Metaconglomerate formed through burial metamorphism. When it forms, the calcite crystals tend to grow larger, and any sedimentary textures and fossils that might have been present are destroyed. The same way a person may cast a shadow over another person when they stand under the sun, planets or celestial bodies that have aligned themselves cast shadows over one another as well. Rocks that form from regional metamorphism are likely to be foliated because of the strong directional pressure of converging plates. It is a low-grade metamorphic rock that splits into thin pieces. This is a megascopic version of what may occur around porphyroblasts. This is not always the case, however. A rock with visible minerals of mica and with small crystals of andalusite. Figure 6.10 Metaconglomerate with elongated of quartz pebbles. List of Geologically Important Elements and the Periodic Table. Foliated metamorphic rocks have elongated crystals that are oriented in a preferred direction. In some cases, hornfels has visible crystals of minerals like biotite or andalusite. Essentials of Geology, 3rd Ed, Stephen Marshak. 2023 Leaf Group Ltd. / Leaf Group Media, All Rights Reserved. This means that the minerals in the rock are all aligned with each other. Massive (non-foliated) structure. Chapter 6 Sediments and Sedimentary Rocks, Chapter 21 Geological History of Western Canada, Next: 7.3 Plate Tectonics and Metamorphism, Creative Commons Attribution 4.0 International License. Examples of nonfoliated metamorphic rocks include marbles, quartzites and soapstones. Metaconglomerate. Even though the quartz crystals themselves are not aligned, the mass of quartz crystals forms a lens that does follow the general trend of alignment within the rock. (1998). Marble is made of dolomite or calcite, and they result from the metamorphism of limestone or dolostone. Differential stress has caused quartz pebbles within the rock to become elongated, and it has also caused wings to form around some of the pebbles (see the pebble in the dashed ellipse). Some types of metamorphism are characteristic of specific plate tectonic settings, but others are not. Rockman's metamorphic rock specimens are hand broken as opposed to being crushed which helps keep cleavage and fracture characteristics intact. On this Wikipedia the language links are at the top of the page across from the article title. There are two major types of structure - foliation and (non-foliated) massive. Regional metamorphism refers to large-scale metamorphism, such as what happens to continental crust along convergent tectonic margins (where plates collide). The mineral alignment in the metamorphic rock called slate is what causes it to break into flat pieces (Figure 10.12, left), and is why slate has been used as a roofing material (Figure 10.12, right). Nonfoliated metamorphic rocks are typically formed in the absence of significant differential pressure or shear. If stress from all directions is equal, place all thin arrows. Skarn is a rock characterized by its formation rather than its mineral composition. Foliated metamorphic rocks exhibit layers or stripes caused by the elongation and alignment of minerals in the rock as it undergoes metamorphism. b. Hutton. . Any rock that contains more than one kind of mineral can be the protolith for gneiss, which is the name for a metamorphic rock that exhibits gneissic banding. There are two main types of metamorphic rocks: those that are foliated because they have formed in an environment with either directed pressure or shear stress, and those that are not foliated because they have formed in an environment without directed pressure or relatively near the surface with very little pressure at all. Metaconglomerate is a rock type which originated from conglomerate after undergoing metamorphism. Any type of magma body can lead to contact metamorphism, from a thin dyke to a large stock. It affects a narrow region near the fault, and rocks nearby may appear unaffected. Photographs and brief descriptions of some common types of metamorphic rocks are shown on this page. Therefore, a simplified system is used based on texture and composition. Typical examples of metamorphic rocks include porphyroblastic schists where large, oblate minerals form an alignment either due to growth or rotation in the groundmass. In most cases, this is because they are not buried deeply, and the heat for the metamorphism comes from a body of magma that has moved into the upper part of the crust. The deeper rocks are within the stack, the higher the pressures and temperatures, and the higher the grade of metamorphism that occurs. Often, retrograde metamorphism will not form a foliation because the unroofing of a metamorphic belt is not accompanied by significant compressive stress. A gentle impact can hit with 40 GPa and raise temperatures up to 500 C. Alignment of tabular minerals in metamorphic rocks, igneous rocks and intrusive rocks may form a foliation. VALLEY, John W.1, CAVOSIE, A.J., WILDE, S.A., GRANT, M., and LIU, Dunyi, http://gsa.confex.com/gsa/2002AM/finalprogram/abstract_39602.htm, ftp://rock.geosociety.org/pub/reposit/2002/2002034.pdf, https://en.wikipedia.org/w/index.php?title=Metaconglomerate&oldid=1007375955, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 17 February 2021, at 20:28. The specimen shown above is about two inches (five centimeters) across. Considering that the normal geothermal gradient (the rate of increase in temperature with depth) is around 30C per kilometer in the crust, rock buried to 9 km below sea level in this situation could be close to 18 km below the surface of the ground, and it is reasonable to expect temperatures up to 500C. In sheared zones, however, planar fabric within a rock may not be directly perpendicular to the principal stress direction due to rotation, mass transport, and shortening. At higher pressures and temperatures, grains and crystals in the rock may deform without breaking into pieces (Figure 6.34, left). A large intrusion will contain more thermal energy and will cool much more slowly than a small one, and therefore will provide a longer time and more heat for metamorphism. As a rock heats up, the minerals that melt at the lowest temperatures will melt first. Introduction to Hydrology and Glaciers, 13a. It is common to use the terms granite and marble to describe rocks that are neither. Click on image to see enlarged photo. Usually, this represents the protolith chemistry, which forms distinct mineral assemblages. The surface of phyllite is typically lustrous and sometimes wrinkled. Metaconglomerate is a rock type which originated from conglomerate after undergoing metamorphism. Where the object hits, pressures and temperatures become very high in a fraction of a second. Labels may be used only once. NONFOLIATED METAMORPHIC ROCKS As opposed to the foliated metamorphic rocks, the nonfoliated rocks are not distinctly layered. Introduction to Geology of the Oceans, 17a Introduction to Human Relationships with Earth Processes. A fourth type of foliated metamorphic rock is called slate. Foliation may parallel original sedimentary bedding, but more often is oriented at some angle to it. Foliation is usually formed by the preferred orientation of minerals within a rock. It is foliated, crenulated, and fine-grained with a sparkly appearance. This forms planes of weakness, and when these rocks break, they tend to break along surfaces that parallel the orientation of the aligned minerals (Figure 10.11). Both are black in color , and is composed of carbon. Texture is divided into two groups. The specimen shown above is about three inches across. The rock also has a strong slaty foliation, which is horizontal in this view, and has developed because the rock was being squeezed during metamorphism. The planar fabric of a foliation typically forms at right angles to the maximum principal stress direction. METACONGLOMERATE The parent rock for metaconglomerate is the sedimentary rock . Foliated metamorphic rocks have a layered or banded appearance that is produced by exposure to heat and directed pressure. Geologic unit mapped in Maryland: Silvery-gray, well foliated, micaceous quartz-pebble metaconglomerate and quartzite; apparent maximum thickness 700 feet. 1. Introduction to Hydrology and Shorelines, 14a. Most sandstone contains some clay minerals and may also include other minerals such as feldspar or fragments of rock, so most quartzite has some impurities with the quartz. Heat is important in contact metamorphism, but pressure is not a key factor, so contact metamorphism produces non-foliated metamorphic rocks such as hornfels, marble, and quartzite. It can refer to green mica minerals, or metamorphic rocks that contain enough green mica to impart a green color. Introduction to Hydrology and Rivers, 11a. The Himalaya range is an example of where regional metamorphism is happening because two continents are colliding (Figure 6.25). Territories. If you have never seen or even heard of blueschist, that not surprising. Adding foil creates a layer, so foliated rocks are layered rocks. Materials in metamorphic rock (e.g., minerals, crystals, clasts) may exhibit orientations that are relatively random or preferred (aligned). Partial melting occurs when the temperature on a rock is high enough to melt only some of the minerals in the rock. Protolith Basalt Conglomerate Dolostone Limestone Granite Sandstone Shale Metamorphic rock Amphibolite Gneiss Marble Metaconglomerate Quartzite Slate Basalt-Amphibolite One such place is the area around San Francisco. Essentially, the minerals are randomly oriented. The outcome of metamorphism depends on pressure, temperature, and the abundance of fluid involved, and there are many settings with unique combinations of these factors. Easy to carve, soapstone was traditionally used by Native Americans for making tools and implements. It often forms when carbonate rocks near a magma body are altered by contact metamorphism and metasomatism. Quartzite is metamorphosed sandstone (Figure 7.11). Foliation may be formed by realignment of micas and clays via physical rotation of the minerals within the rock. Learn more about how Pressbooks supports open publishing practices. There is no evidence of foliation. These rocks are all foliated because of the strong compressing force of the converging plates. Contact metamorphism can take place over a wide range of temperaturesfrom around 300 C to over 800 C. answer choices. The stress that produced this pattern was greatest in the direction indicated by the black arrows, at a right angle to the orientation of the minerals. Jurassic metaconglomerate bij Los Peasquitos Canyon Preserve , San Diego County, Californi . Novaculite is a dense, hard, fine-grained, siliceous rock that breaks with a conchoidal fracture. A rock that is dominated by aligned crystals of amphibole. Shale, slate, phyllite, schist, gneiss, partial melting Match each rock with its first-order metamorphic equivalent (the first rock it would turn into when metamorphosed). Often this foliation is associated with diagenetic metamorphism and low-grade burial metamorphism. This is probably because nonfoliated rocks were exposed to high temperature conditions, but not to high directional pressure conditions. University of Notre Dame: Prograde Metamorphism. The grains form a mosaic texture. You can help Wikipedia by expanding it. Sedimentary rocks have been both thrust up to great heightsnearly 9 km above sea leveland also buried to great depths. Generally, the acute intersection angle shows the direction of transport. . Another type of foliated metamorphic rock is called schist. Anthracite coal is generally shiny in appearance and breaks with a conchoidal fracture (broken glass also shows this type of fracture). Rocks exhibiting foliation include the standard sequence formed by the prograde metamorphism of mudrocks; slate, phyllite, schist and gneiss. Although bodies of magma can form in a variety of settings, one place magma is produced in abundance, and where contact metamorphism can take place, is along convergent boundaries with subduction zones, where volcanic arcs form (Figure 6.31). It has been exposed to enough heat and pressure that most of the oxygen and hydrogen have been driven off, leaving a high-carbon material behind. It is composed primarily of calcium carbonate. Granite may form foliation due to frictional drag on viscous magma by the wall rocks. Notice the sequence of rocks that from, beginning with slate higher up where pressures and temperatures are lower, and ending in migmatite at the bottom where temperatures are so high that some of the minerals start to melt. Our goal is to make science relevant and fun for everyone. If you happen to be in the market for stone countertops and are concerned about getting a natural product, it is best to ask lots of questions. Question 14. Foliation means the alignment within a metamorphic rock. There are two basic types of metamorphic rocks. Quartz has a hardness of 7, which makes it difficult to scratch. Foliation, as it forms generally perpendicular to the direction of principal stress, records the direction of shortening. Block-in-matrix structures are observed in these exposures, including a large metaconglomerate block (10s m in diameter) found at . In only a few places in the world, the subduction process was interrupted, and partially subducted blueschist returned to the surface. As already noted, slate is formed from the low-grade metamorphism of shale, and has microscopic clay and mica crystals that have grown perpendicular to the stress. Foliated textures show a distinct planar character. Even if formed during regional metamorphism, quartzite does not tend to be foliated because quartz crystals dont align with the directional pressure. Metamorphism and Metamorphic Rocks, Chapter 17: Humans' Relationship to Earth Processes, Physical Geology, First University of Saskatchewan Edition, Next: 6.5 Metamorphic Facies and Index Minerals, Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Crenulation cleavage and oblique foliation are particular types of foliation. 30 seconds. Textures Non-foliated or granular metamorphic rocks are those which are composed of equi-dimensional grains such as quartz or calcite. Created by unique combinations of minerals and metamorphic conditions, these rocks are classified by their chemical compositions. As already noted, slate is formed from the low-grade metamorphism of shale, and has microscopic clay and mica crystals that have grown perpendicular to the stress. c. hydrothermal. Metamorphic rock may exhibit a variety of features related to the organization and arrangement of its component materials. Slate is a foliated metamorphic rock that is formed through the metamorphism of shale. It is composed primarily of hornblende (amphibole) and plagioclase, usually with very little quartz. Non . Principles of Earth Science by Katharine Solada and K. Sean Daniels is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted. Metamorphism and Metamorphic Rocks, Chapter 13. This planar character can be flat like a piece of slate or folded. Most foliation develops when new minerals are forced to grow perpendicular to the direction of greatest stress. At an oceanic spreading ridge, recently formed oceanic crust of gabbro and basalt is slowly moving away from the plate boundary (Figure 6.26). The tendency of slate to break into flat pieces is called slaty cleavage. Marble and hornfels are metamorphic rock types that typically do not typically show observable foliation. The planar fabric of a foliation typically forms at right angles to the maximum principal stress direction. Thick arrows pointing down and up. Preface to the First University of Saskatchewan Edition, Second University of Saskatchewan Edition: Goals, 1.4 We Study Earth Using the Scientific Method, 1.5 Three Big Ideas: Geological Time, Uniformitarianism, and Plate Tectonics, 2.2 Forming Planets from the Remnants of Exploded Stars, 3.1 Earth's Layers: Crust, Mantle, and Core, 4.1 Alfred Wegener's Arguments for Plate Tectonics, 4.2 Global Geological Models of the Early 20th Century, 4.3 Geological Renaissance of the Mid-20th Century, 4.4 Plates, Plate Motions, and Plate-Boundary Processes, 8.3 Controls on Weathering Processes and Rates, 8.4 Weathering and Erosion Produce Sediments, 9.2 Chemical and Biochemical Sedimentary Rocks, 9.4 Depositional Environments and Sedimentary Basins, 10.4 Types of Metamorphism and Where They Occur, 10.5 Metamorphic Facies and Index Minerals, 10.6 Metamorphic Hydrothermal Processes and Metasomatism, 11.2 Materials Produced by Volcanic Eruptions, 11.7 Monitoring Volcanoes and Predicting Eruptions, 12.5 Forecasting Earthquakes and Minimizing Impacts, 15.1 Factors That Control Slope Stability, 15.3 Preventing, Delaying, Monitoring, and Mitigating Mass Wasting, 18.1 If You Can't Grow It, You Have to Mine It, Appendix A. The force of the collision causes rocks to be folded, broken, and stacked on each other, so not only is there the squeezing force from the collision, but from the weight of stacked rocks. Regional metamorphism also takes place in this setting, and because of the extra heat associated with the magmatic activity, the geothermal gradient is typically steeper in these settings (between ~40 and 50 C/km). When extraterrestrial objects hit Earth, the result is a shock wave. Schist is a metamorphic rock with well-developed foliation. Notice: Unless otherwise noted, all images and graphics contained within are the property of Richard Harwood and may only be reproduced with permission from the author. That means it will take a long time to heat up, can be several hundreds of degrees cooler than the surrounding mantle. This will allow the heat to extend farther into the country rock, creating a larger aureole. Drag the appropriate labels to their respective targets. The specimen shown above is a "chlorite schist" because it contains a significant amount of chlorite. Fractional crystallization is the opposite of partial melting. An example of this is shown in Figure 7.12. Essentially, the minerals are randomly oriented. Quartzite is composed of quartz sand grains. As metamorphic processes go, burial metamorphism takes place at relatively low temperatures (up to ~300 C) and pressures (100s of m depth). Springer. The intense heat and pressure of metamorphism . It is intermediate in grade between slate and schist. . Rock cleavage is what caused the boulder in Figure 10.8 to split from bedrock in a way that left the flat upper surface upon which the geologist is sitting. Thus, aureoles that form around wet intrusions tend to be larger than those forming around their dry counterparts. One kind of foliation is called gneissic banding, which looks like bands of light and dark layers. The passage of this water through the oceanic crust at these temperatures promotes metamorphic reactions that change the original olivine and pyroxene minerals in the rock to chlorite ((Mg5Al)(AlSi3)O10(OH)8) and serpentine ((Mg,Fe)3Si2O5(OH)4). Slate exhibits slaty foliation, which is also called cleavage. In geotechnical engineering a foliation plane may form a discontinuity that may have a large influence on the mechanical behavior (strength, deformation, etc.) Some rocks, such as granite, do not change much at the lower metamorphic grades because their minerals are still stable up to several hundred degrees. Dynamic metamorphism occurs at relatively low temperatures compared to other types of metamorphism, and consists predominantly of the physical changes that happen to a rock experiencing shear stress. 2. Molecular Biology and Genetics. Metamorphic rocks are rocks that have been changed either in texture or in mineral composition by the influence of heat, pressure, stress (directed pressure), chemically active solutions or gasses or some other agent without the rock passing through a liquid phase. This is related to the axis of folds, which generally form an axial-planar foliation within their axial regions. This planar character can be flat like a piece of slate or folded. Place the thick arrows in the direction of maximum stress and the thin arrows in the direction of minimum stress. Supplying quality educational materials for teachers, collectors and other educational organizations since 1995. What is surprising is that anyone has seen it! Foliation With wavy layering known as phyllitic foliation, these rocks often have a silky or satiny sheen, which is caused by the arrangement of very fine minerals that form as a result of the pressure applied during metamorphism. The layers form parallel to the direction of the shear, or perpendicular to the direction of higher pressure. (PDF) Petrostructural Features of Metaconglomerate in Igarra and Otuo, South-Western Nigeria Petrostructural Features of Metaconglomerate in Igarra and Otuo, South-Western Nigeria Authors:. HyperPhysics*****Geophysics: Chapter 2. Non-foliated rocks - quartzite, marble, hornfels, greenstone, granulite ; Mineral zones are used to recognize metamorphic facies produced by systematic pressure and temperature changes. Well foliated to nearly massive quartz monzonite gneiss, generally medium-grained and even textured but locally porphyritic and pegmatitic. Want to create or adapt OER like this? Phyllite is a foliated metamorphic rock that is made up mainly of very fine-grained mica. Weakly foliated: Any material: Hard, fine-grained rock: Metaconglomerate: Weakly foliated: Quartz-rich conglomerate: Strongly stretched pebbles: Amphibolite: Weakly foliated: Mafic volcanic rocks: Coarse-grained: Examples of metamorphic rock: Index Reference Lutgens and Tarbuck Ch 7 . There are many other types of specific nonfoliated metamorphic rocks, such as greenstone, eclogites and serpentines. The general term for the property of alignment in metamorphic rock is foliation, of which there are a number of types. Foliated metamorphic rocks have a layered or banded appearance that is produced by exposure to heat and directed pressure. It typically contains abundant quartz or feldspar minerals. However, a more complete name of each particular type of foliated metamorphic rock includes the main minerals that the rock comprises, such as biotite-garnet schist rather than just schist. Click on image to see enlarged photo. Foliated metamorphic rocks exhibit layers or stripes caused by the elongation and alignment of minerals in the rock as it undergoes metamorphism. In geology, cleavage refers to the tendency of a rock to break parallel to the alignment of the tiny mica minerals it is composed of. As already noted, the nature of the parent rock controls the types of metamorphic rocks that can form from it under differing metamorphic conditions. At lower pressures and temperatures, dynamic metamorphism will have the effect of breaking and grinding rock, creating cataclastic rocks such as fault breccia (Figure 6.33). On the other hand, any clay present in the original sandstone is likely to be converted to mica during metamorphism, and any such mica is likely to align with the directional pressure. Exposure to these extreme conditions has altered the mineralogy, texture, and chemical composition of the rocks. The pebbles have developed "wings" to varying degrees (e.g., white dashed ellipse). . In this treatment, we'll describe metamorphic rock that does not show visible alignment of materials as massive. Under these conditions, higher grades of metamorphism can take place closer to surface than is the case in other areas. The rock in Figure 10.10 had a quartz-rich conglomerate as a parent rock. Unlike slate and phyllite, which typically only form from mudrock, schist, and especially gneiss, can form from a variety of parent rocks, including mudrock, sandstone, conglomerate, and a range of both volcanic and intrusive igneous rocks. One derived from shale may be a muscovite-biotite schist, or just a mica schist, or if there are garnets present it might be mica-garnet schist. [1] The word comes from the Latin folium, meaning "leaf", and refers to the sheet-like planar structure. Schistose foliation is composed of larger minerals which are visible to the unaided eye. 1. The specimen shown above is about two inches (five centimeters) across. Foliation in areas of shearing, and within the plane of thrust faults, can provide information on the transport direction or sense of movement on the thrust or shear. The specimen above is about two inches (five centimeters) across. This is illustrated in Figure 7.6, where the parent rock is shale, with bedding as shown. This contributes to the formation of foliation. The cement matrix of conglomerate is not as durable as the grains, and hence when broken, conglomerate breaks around the grains. Further identification of non-foliated rocks is dependent on the composition of the minerals or components in the rock. When describing a foliation it is useful to note. The location of the wings depends on the distribution of stress on the rock (Figure 10.10, upper right). Traces of Catastrophe: A Handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures. The outcome of prolonged dynamic metamorphism under these conditions is a rock called mylonite, in which crystals have been stretched into thin ribbons (Figure 6.34, right). Silvery-gray, well foliated, micaceous quartz-pebble metaconglomerate and quartzite; apparent maximum thickness 700 feet. foliated metamorphic describes the texture of metamorphic rock Related questions What are some example names of foliated and un-foliated rocks? Marble is composed of calcite and will readily react to a small drop of HCl. Foliated textures show four types of foliation. If the original rock had bedding (represented by diagonal lines in Figure 10.7, right), foliation may obscure the bedding. Squeezing and heating alone (as shown in Figure 7.5) and squeezing, heating, and formation of new minerals (as shown in Figure 7.6) can contribute to foliation, but most foliation develops when new minerals are forced to grow perpendicular to the direction of greatest stress (Figure 7.6). Non-foliated textures have minerals that are not aligned. For example a schist derived from basalt is typically rich in the mineral chlorite, so we call it chlorite schist. Igneous rocks can become foliated by alignment of cumulate crystals during convection in large magma chambers, especially ultramafic intrusions, and typically plagioclase laths. If a rock is both heated and squeezed during metamorphism, and the temperature change is enough for new minerals to form from existing ones, the new minerals can be forced to grow longer perpendicular to the direction of squeezing (Figure 10.7).