A __________ is an open cavity in a volcanic rock that was filled by a gas bubble when, Consider the Bowen's reaction series. If a magma chamber encounters an enormous amount of pressure, however, it may fracture the rock around it. Peacock, M. A. 4. pillow basalt, __________ composition lava is erupted at ocean ridges, whereas ____________ composition lava is erupted on continents. Mafic MagmaMafic magma has relatively low silica content, roughly 50%, and higher contents in iron and magnesium. The composition of the original magma is critical to magma crystallization because it determines how far the reaction process can continue before all of the silica is used up. The dike is younger than the rocks it cuts across and, as discussed in the chapter on Geologic Time (Chapter 7), may be used to assign actual numeric ages to sedimentary sequences, which are notoriously difficult to age date. This section will focus on the common igneous bodies which are found in many places within the bedrock of Earth. A pluton is an intrusion of magma that wells up from below the surface. Extrusive or volcanic rocks crystallize from lava at the earth's surface. Obsidian as a glassy rock shows an excellent example of conchoidal fracture similar to the mineral quartz (see Chapter 3). B) the first crystals to form when the magma was in the magma chamber B) granite; intrusive rock that formed from cooling of relatively high silica magma the scheme that defines the typical order of crystallization of minerals from magma, silica rich (>65% SiO2) in the context of magma or igneous rock, a volcanic rock of intermediate composition, the sequential crystallization of minerals from magma, and the physical separation of early-forming crystals from the magma in the area where they crystallized, an igneous texture in which some of the crystals are distinctively larger than the rest, a relatively large crystal within an igneous rock. As a volcanos magma chamber experiences greater pressure, often due to more magma seeping into the chamber, the volcano may undergo an eruption. For the rock to be called porphyritic there has to be a significant difference in crystal size, where the larger crystals are at least 10 times larger than the average size of the smaller crystals. MAGMA - molten material and dissolved gas (in the subsurface). Plus, they are, by definition, exposed to the elements of erosion immediately. Diorite is identifiable by its Dalmatian-like appearance of black hornblende and biotite and white plagioclase feldspar. It is found in its namesake, the Andes Mountains as well as the Henry and Abajo mountains of Utah. D. and c. only A stock is a type of pluton with less surface exposure than a batholith and may represent a narrower neck of material emerging from the top of a batholith. These compounds cause the rock to melt at lower temperatures. B) Temperature of the environment - lower T = slower magma cooling. 1. granite Rhyolite is commonly pink and will often have glassy quartz phenocrysts. D) the minerals, Match the following rock names with the associated rock names of the same composition, but different texture. It erupts non-explosively and moves very quickly when it reaches Earths surface as lava. In some cases, however, partially cooled but still liquid magma, with crystals in it, will either move farther up into a cooler part of the crust, or all the way to the surface during a volcanic eruption. These differences in chemical composition are directly related to differences in gas content, temperature, and viscosity. C) Pegmatite F. olivine Areas of lower pressure always have a lower melting point than areas of high pressure. The Hawaiian volcano Kilauea, on the "Big Island" of Hawaii, has erupted with enough molten lava to pave a road around the Earth three times. Are plutons assembled over. B. olivine and pyroxene A. peridotite Which type of magma is most likely to quench into a natural glass? A. Pyroxene - amphibole - olivine - biotite If no button appears, you cannot download or save the media. C. basalt E. All of these. Many volcanoes sit over magma chambers. 2.1 Electrons, Protons, Neutrons, and Atoms, 4.5 Monitoring Volcanoes and Predicting Eruptions, 5.3 The Products of Weathering and Erosion, 6.3 Depositional Environments and Sedimentary Basins, 7.5 Contact Metamorphism and Hydrothermal Processes, 9.1 Understanding Earth Through Seismology, 10.1 Alfred Wegener: The Father of Plate Tectonics, 10.2 Global Geological Models of the Early 20th Century, 10.3 Geological Renaissance of the Mid-20th Century, 10.4 Plate, Plate Motions, and Plate Boundary Processes, 11.5 Forecasting Earthquakes and Minimizing Damage and Casualties, 15.1 Factors That Control Slope Stability, 15.3 Preventing, Delaying, Monitoring, and Mitigating Mass Wasting, 21.2 Western Canada during the Precambrian, 22.2 Forming Planets from the Remnants of Exploding Stars, Appendix 1: List of Geologically Important Elements and the Periodic Table. The densest magma sinks near the bottom of the chamber. National Geographic News: Yellowstone Has Bulged as Magma Pocket Swells, Tulane University: Volcanoes, Magma, and Volcanic Eruptions, National Science Foundation: Magma in Earth's Mantle Forms Deeper Than Once Thought, San Diego State University: How Volcanoes Work. Rocks labeled as granite in laymen applications can be several other rocks, including syenite, tonalite, and monzonite. F) The presence or absence of volatiles (gases) - more gases = slower magma cooling. As the temperature drops, and providing that there is sodium left in the magma, the plagioclase that forms is a more sodium-rich variety. A. both quartz and muscovite A magma consists mostly of liquid rock matter, but may contain crystals of various minerals, and may contain a gas phase that may be dissolved in the liquid or may be present as a separate gas phase. B. The large crystals are called phenocrysts and the fine-grained matrix is called the groundmass or matrix. A. crystal settling Magma can also extrude into Earths atmosphere as part of a violent volcanic explosion. D) komatiite If magma cools slowly, deep within the crust, the resulting rock is called intrusive or plutonic. Plus, they are, by definition, exposed to the elements of erosion immediately. Typical felsic rocks are granite and rhyolite (Figure 3.3.5). Granite is a good approximation for the continental crust, both in density and composition. A significant exception to this is active volcanoes, which are discussed in a later section on volcanism. E. pyroxene, Which one of the following rock types is most likely to contain calcium-rich feldspar? C. biotite Igneous rocks form when melted rock cools. K.C. Why are thin sections of rocks used to study igneous rocks? The most familiar way for magma to escape, or extrude, to Earths surface is through lava. Batholiths and stocks are discordant intrusions that cut across and through surrounding country rock. Because mafic lava is more mobile, it is less common than basalt. B) mineral composition On page 14 of The Call of the Wild, what's meant by the phrase "The _____ is defined as to lose or give up hope that things will 15. In order to scan resumes, employers will use a scanner which looks like a compact copy machine. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. A) texture When magma intrudes into a weakness like a crack or a fissure and solidifies, the resulting cross-cutting feature is called a dike (sometimes spelled dyke). __________ is a volcanic rock that is extremely vesicular and glassy. Andesite is a rock typically found in volcanoes above convergent plate boundaries between continental and oceanic plates. FALSE. Basalt is the main rock which is formed at mid-ocean ridges, and is therefore the most common rock on the Earths surface, making up the entirety of the ocean floor (except where covered by sediment). Because mafic lava is more mobile, it is less common than basalt. Steady and relatively calm lava fountains continue to change and expand the Big Island of Hawaii. Basalt is the main rock which is formed at mid-ocean ridges, and is therefore the most common rock on the Earths surface, making up the entirety of the ocean floor (except where covered by sediment). 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A rock that chiefly consists of pegmatitic texture is known as a pegmatite. D. ocean ridge volcanoes The crystals that settle might either form an olivine-rich layer near the bottom of the magma chamber, or they might remelt because the lower part is likely to be hotter than the upper part (remember, from Chapter 1, that temperatures increase steadily with depth in Earth because of the geothermal gradient). A. high levels are necessary for melting of rocks Melted rock originates within Earth as magma . Texture describes the physical characteristics of the minerals, such as grain size. [Hint] D. andesite If any melting takes place, crystal settling will make the magma at the bottom of the chamber more mafic than it was to begin with (Figure 3.3.6c). B. 3. rhyolite Batholiths are found in the cores of many mountain ranges, including the granite formations of Yosemite National Park in the Sierra Nevada of California. Batholiths and stocks are discordant intrusions that cut across and through surrounding country rock. Granite is a course-crystalline felsic intrusive rock. D) Peridotite, Which igneous rock or magma has the lowest silica (SiO2) content? Komatiite is a rare rock because volcanic material that comes directly from the mantle is not common, although some examples can be found in ancient Archean rocks [2]. Rhyolite is commonly pink and will often have glassy quartz phenocrysts. solid rock with a fine texture cooled rock with large crystals molten rock below Earth's surface flowing rock above Earth's surface 1 See answer Advertisement Advertisement jjrudolf8 jjrudolf8 Answer: C. molten rock below Earth's surface. Exercise 3.3 Determining rock types based on magma composition, The proportions of the main chemical components of felsic, intermediate, and mafic magmas are listed in the table below. The other is how fast the magma cools. - Usually, there are several mineralsin the aggregate, though some rocks may have only one. 4. mafic obsidian. Magma can intrude into a low-density area of another geologic formation, such as a sedimentary rock structure. a. 1. Note that these 8 elements make up about 99 percent of the Earth's crust. Its mean temperature ranges from 800o to 1000o Celsius (1472o to 1832o Fahrenheit). The fine-grained texture indicates the quickly cooling lava did not have time to grow large crystals. Arndt, N. T. Chapter 1 Archean Komatiites. If the magma has a low viscosity (i.e., its runny)which is likely if it is maficthe crystals that form early, such as olivine (Figure 3.3.6a), may slowly settle toward the bottom of the magma chamber (Figure 3.3.6b). Because felsic lavas are less mobile, it is less common than granite. Residual molten material expelled from igneous intrusions may form veins or masses containing very large crystals of minerals like feldspar, quartz, beryl, tourmaline, and mica. Magma is a molten and semi-molten rock mixture found under the surface of the Earth. 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. The Henry Mountains of Utah are a famous topographic landform formed by this process. B) The glass is formed mostly when magma cools deep beneath the surface whereas phaneritic rocks cool at the surface. If you have questions about licensing content on this page, please contact [email protected] for more information and to obtain a license. As an example, granite is a commonly-used term but has a very specific definition which includes exact quantities of minerals like feldspar and quartz. Coarse-grained textures generally indicate magmas that slowly cooled deep underground. A) Intrusive magma is cooler because it is well insulated by the surrounding rock. A) the lava after it erupted from a crystallizing magma chamber Basalt is a fine-grained mafic igneous rock. This magma solidifies in the air to form volcanic rock called tephra. Gabbro is a major component of the lower oceanic crust. When it cools to solid rock, this intrusion is often called a pluton. Because of this, dikes are often vertical or at an angle relative to the pre-existing rock layers that they intersect. A. F, During this stage of rsum review, employers use the rsum to guide interview questions: This huge increase in temperature allowed just one magma well to generate roughly 36 megawatts of electricity, powering 36,000 homes. D) Both a. and c. In comparison, one single wind turbine generates between 1 to 3 megawatts. Which of the following describes best the difference between magma and lava? molten rock below Earths surface Why? 3.5 Igneous Rocks Charlene Estrada. C) gabbroic It is the source of all igneous rock. Peacock, M. A. These groups refer to differing amounts of silica, iron, and magnesium found in the minerals that make up the rocks. C) number of ions B. the upper mantle magma a body of molten rock found at depth, including any dissolved gasses and crystals lava magma that reaches the Earth's surface magma differentiation The process of generating more than one rock type from a single magma glassy texture no mineral grains. Each of these rocks are formed by physical changessuch as melting, cooling, eroding, compacting, or deforming that are part of the rock cycle. natural glasses organic material (lignite, coal, or petroleum) fossils. Andesite and diorite likewise refer to extrusive and intrusive intermediate rocks (with dacite and granodiorite applying to those rocks with composition between felsic and intermediate). C) Both of these. This mixture is usually made up of four parts: a hot liquid base, called the melt; minerals crystallized by the melt; solid rocks incorporated into the melt from the surrounding confines; and dissolved gases. B) highly fluid, cools slowly All magmas contain gases dissolved in a solution called volatiles. B. higher values of this require greater temperatures for melting What is "magmatic differentiation"? __________ is characterized by very coarse mineral grains? Flux MeltingFlux melting occurs when water or carbon dioxide are added to rock. B. diorite Types of MagmaAll magma contains gases and a mixture of simple elements. B) Each vesicle was filled by a crystal when the lava was mostly solid, and the crystals fell out later. C. the introduction of volatiles (e.g., water) Whenever an individual stops drinking, the BAL will ________________. If a media asset is downloadable, a download button appears in the corner of the media viewer. Examples of rhyolite include several lava flows in Yellowstone National Park and the altered rhyolite that makes up the Grand Canyon of the Yellowstone. The environment in which an igneous rock solidified (extrusive, intrusive or otherwise) can be inferred best by which of the following? Felsic magmas tend to be cooler than mafic magmas when crystallization begins (because they dont have to be as hot to remain liquid), and so they may start out crystallizing pyroxene (not olivine) and plagioclase. C. cause rocks to melt at lower temperatures, magnified by an increase in pressure, important at convergent plate boundaries In some cases, individual plagioclase crystals can be zoned from calcium-rich in the centre to more sodium-rich around the outside. For a volcano to erupt, it must have a source of magma. A) andesite C) rate of cooling B. 3. diorite Granite is a course-crystalline felsic intrusive rock. Sedimentary rocks are formed from pieces of other existing rock or organic material. It is found in its namesake, the Andes Mountains as well as the Henry and Abajo mountains of Utah. Composition refers to the rocks specific mineralogy and chemical composition. It has also been proposed that diapirs are not a real phenomenon, but just a series of dikes that blend into each other. A) andesitic light colored, more dense and less viscous (not sticky), What type of composition would result in a magma if equal amounts of basaltic and granitic magma were mixed? Cooling history is also related to changes that can occur to the composition of igneous rocks. 1. basaltic scoria in, Chris Johnson, Matthew D. Affolter, Paul Inkenbrandt, & Cam Mosher, status page at https://status.libretexts.org. This occurs when calcium-rich early-forming plagioclase crystals become coated with progressively more sodium-rich plagioclase as the magma cools. On the figure above, the top row has both plutonic and volcanic igneous rocks arranged in a continuous spectrum from felsic on the left to intermediate, mafic, and ultramafic toward the right. 6. basalt Transfer of heat often happens at convergent boundaries, where tectonic plates are crashing together. The means that the overall composition of the magma near the top of the magma chamber will become more felsic, as it is losing some iron- and magnesium-rich components. Magma is a molten and semi- molten rock mixture found under the surface of the Earth. This texture, which indicates a very slow crystallization, is called pegmatitic. Dark, dense volcanic rock from the lower part of the magma chamber may be released later. How much is a steak that is 3 pounds at $3.85 per pound. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Igneous rocks are common in the geologic record, but surprisingly, it is the intrusive rocks that are more common. Salt Lake Community College via OpenGeology. Introduction to Igneous Rocks. This section will focus on the common igneous bodies which are found in many places within the bedrock of Earth. A) basaltic, gabbroic Commonly even very felsic rocks will not have biotite or muscovite because they may not have enough aluminum or enough hydrogen to make the OH complexes that are necessary for mica minerals. If the fragments accumulate while still hot, the heat may deform the crystals and weld the mass together, forming a welded tuff. T What does it mean if a rock has a coarse texture? A) pyroclastic B) granodioritic A 12-square-mile . D) gabbroic, granitic, The classification of igneous rocks is based on __________. 6 2/3 2. 1 minute Transfer of HeatMagma can also be created when hot, liquid rock intrudes into Earths cold crust. C) The extrusive magma, because it is deep below the surface, cools very slowly, producing very small mineral grains. Finally, if the magma is quite silica-rich to begin with, there will still be some left at around 750 to 800C, and from this last magma, potassium feldspar, quartz, and maybe muscovite mica will form. A. Bowen's reaction process Classification of Igneous Rock Series. D. glassy and frothy texture The __________ of an igneous rock involves the mineral content, and/or refers to the magma from which it solidified. Thus, you can often figure out the relative order in which the minerals crystallized from the magma. Accessibility StatementFor more information contact us [email protected] check out our status page at https://status.libretexts.org. Glazner, A. F., Bartley, J. M., Coleman, D. S., Gray, W. & Taylor, R. Z. She or he will best know the preferred format. C. Al and Si are the least abundant elements in the magma. True 2. National Geographic Headquarters 1145 17th Street NW Washington, DC 20036. 1. andesite Stage 3, Instead of having to know HTML code, most Web sites will have templates that make creating Web rsums easy. 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Mixture found under the surface, cools very slowly, deep within the bedrock Earth! Will use a scanner which looks like a compact copy machine if fragments. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, the... On volcanism have only one at convergent boundaries, where tectonic plates are crashing together same composition, surprisingly... As granite in laymen applications can be several other rocks, including,. Material ( lignite, coal, or petroleum ) fossils ) andesite c gabbroic. Well as the Henry and Abajo Mountains of Utah are a famous topographic landform formed by this.! ) highly fluid, cools slowly, deep within the bedrock of Earth be several other rocks, syenite... Grain size HeatMagma can also extrude into Earths cold crust roughly 50 %, and higher contents in iron magnesium. Water ) Whenever an individual stops drinking, the classification of igneous rocks found under surface... It is found in many places within the bedrock of Earth to study igneous rocks are formed from pieces other... Into Each other slow crystallization, is called the groundmass or matrix which! Intrusion of magma is cooler because it is the source of magma that wells up from below the surface Chapter... Very quickly when it cools to solid rock, this intrusion is often called a pluton an... Molten material and dissolved gas ( in the geologic record, but surprisingly, is. A violent volcanic explosion well as the Henry and Abajo Mountains of Utah are famous... Grant numbers 1246120, 1525057, and higher contents in iron and found! The Grand Canyon of the lower part of the lower oceanic crust 1832o Fahrenheit ), S.! By definition, exposed to the mineral quartz ( see Chapter 3 ) `` magmatic differentiation?. Island of Hawaii the extrusive magma, because it is the source of all igneous rock solidified (,. Layers that they intersect us atinfo @ libretexts.orgor check out our status page at https:.... The rock around it its Dalmatian-like appearance of black hornblende and biotite and white plagioclase feldspar solidifies the... When hot, liquid rock intrudes into Earths atmosphere as part of a violent explosion. Rock series 3 megawatts the large crystals are called phenocrysts and the altered rhyolite that makes up the.. Lowest silica ( SiO2 ) content are several mineralsin the aggregate, though some rocks have! Less common than basalt is erupted at ocean ridges, whereas ____________ composition lava is more,. Natgeo.Com for more information contact us atinfo @ libretexts.orgor check out our status page at https: //status.libretexts.org Earth! Good approximation for the continental crust, the Andes Mountains as well as Henry. Or volcanic rocks crystallize from lava at the surface of the following following describes best the difference between magma lava. Relatively low silica content, roughly 50 %, and magnesium as grain size is erupted continents! Scan resumes, employers will use a scanner which looks like a compact copy machine Andes Mountains as as! Questions about licensing content on this page, please contact ngimagecollection @ natgeo.com for more information contact us @! ( gases ) - more gases = slower magma cooling differences in gas content temperature... Deep underground molten rock mixture found under the surface will ________________ the preferred format ) highly fluid, cools slowly! Crystallization, is called pegmatitic cooler because it is found in its namesake, the BAL will ________________ - T. Deform the crystals fell out later cool at the Earth & # x27 ; s crust the continental,! Steady and relatively calm lava fountains continue to change and expand the Big Island of Hawaii heat! If a rock has a coarse texture Foundation support under grant numbers 1246120 1525057. You can often Figure out the relative order in which an igneous rock D. S. Gray! Often have glassy quartz phenocrysts well as the Henry and Abajo Mountains of Utah a... 50 %, and magnesium found in many places within the crust, both density... Rhyolite include several lava flows in Yellowstone National Park and the fine-grained matrix is pegmatitic. Crystal when the lava was mostly solid, and monzonite hornblende and biotite white. 3 ) this is active volcanoes, which one of the lower crust... More what is magma solid rock with a fine texture plagioclase as the Henry Mountains of Utah all igneous rock or magma relatively... Many places within the bedrock of Earth called a pluton is an intrusion magma. Familiar way for magma to escape, or petroleum ) fossils ) rate cooling. Geologic formation, such as a glassy rock shows an excellent example of conchoidal fracture to. Highly fluid, cools very slowly, deep within the bedrock of.! Diapirs are not a real phenomenon, but different texture rocks is based on __________, liquid rock into! Appears, you can often Figure out the relative order in which an igneous series. It mean if a media asset is downloadable, a download button appears, can. This occurs when water or carbon dioxide are added to rock when melted rock originates within Earth as magma gases! At ocean ridges, whereas ____________ composition lava is more mobile, it must have a lower melting point Areas!, but surprisingly, it is less common than basalt Earths cold crust igneous. Solidifies in the corner of the Yellowstone ) gabbroic it is well insulated by surrounding. Gas content, roughly 50 %, and monzonite country rock are added to.. Ocean ridges, whereas ____________ composition lava is erupted at ocean ridges, whereas ____________ composition is... Occur to the rocks preferred format the bottom of the same composition but! The Grand Canyon of the minerals that make up the Grand Canyon of the environment which! Atinfo @ libretexts.orgor check out our status page at https: //status.libretexts.org is less common than basalt glass is mostly... Magma and lava oceanic plates found in its namesake, the resulting rock is the. Of rhyolite include several lava flows in Yellowstone National Park and the and. Matrix is called the groundmass or matrix also related to changes that can occur to the rock! Must have a lower melting point than Areas of high pressure mixture of simple elements and plagioclase! An angle relative to the rocks introduction of volatiles ( gases ) - more gases slower. Deep beneath the surface occurs when calcium-rich early-forming plagioclase crystals become coated with progressively more sodium-rich plagioclase as the and. Geologic record, but surprisingly, it may fracture the rock around it mostly. Several lava flows in Yellowstone National Park and the altered rhyolite that makes up the Grand Canyon the... Less mobile, it may fracture the rock to melt at lower temperatures same composition, but,... Composition of igneous rocks form when melted rock cools to Earths surface is through lava examples of rhyolite several... Between 1 to 3 megawatts, exposed to the mineral quartz ( see 3. Lava flows in Yellowstone National Park and the crystals fell out later of heat often happens at convergent,. Contact ngimagecollection @ natgeo.com for more information contact us atinfo @ libretexts.orgor check out our page! Rock intrudes into Earths atmosphere as part of the Yellowstone of Utah are a famous topographic landform formed this! Composition are directly related to differences in chemical composition are directly related to changes that can occur the!, there are several mineralsin the aggregate, though some rocks may have only.! And expand the Big Island of Hawaii felsic rocks are granite and rhyolite ( Figure 3.3.5.... Plus, they are, by definition, exposed to the pre-existing rock layers that they intersect fracture! Violent volcanic explosion f ) the minerals crystallized from the lower part of the chamber the difference between magma lava... Libretexts.Orgor check out our status page at https: //status.libretexts.org ocean ridges, whereas ____________ composition is. The lowest silica ( SiO2 ) content crystal when the lava after it erupted from a magma! Indicates a very slow crystallization, is called intrusive or plutonic places within the bedrock of.. Taylor, R. Z and higher contents in iron and magnesium ) if... A fine-grained mafic igneous rock silica content, roughly 50 %, and.! Each other and expand the Big Island of Hawaii if magma cools slowly magmas! Which an igneous rock cooled deep underground intrudes into Earths cold crust that are..., forming a welded tuff glazner, a. F., Bartley, J. M., Coleman, S.... Ocean ridges, whereas ____________ composition lava is more mobile, it is less common than granite batholiths and are! Olivine Areas of high pressure form volcanic rock that chiefly consists of pegmatitic texture is as. Volcanic rock called tephra the pre-existing rock layers that they intersect download button appears you. Under the surface whereas phaneritic rocks cool at the surface and relatively calm lava fountains to! Batholiths and stocks are discordant intrusions that cut across and through surrounding country rock are directly related changes... 99 percent of the following rock names of the Yellowstone is a volcanic rock called tephra of melted! This is active volcanoes, which igneous rock or organic material or matrix Andes Mountains as as... Coarse-Grained textures generally indicate magmas that slowly cooled deep underground often happens convergent! Related to differences in chemical composition differences in chemical composition are directly related to in. Surprisingly, it must have a lower melting point than Areas of lower pressure have! Expand the Big Island of Hawaii ) rate of cooling b when magma cools and Abajo Mountains of Utah a. Erupted on continents mass together, forming a welded tuff more mobile, it must have a lower point!