Question: a finely crystalline or glassy igneous texture indicates that:a. Question: a vesicular igneous texture indicates that:a

Question: a welded igneous texture indicates that:a. Answer: the ash and pumice were hot and became compacted

Question: a porphyritic igneous texture indicates that:a. Question: which of the following rock types requires dissolved gas in the magma?a

Igneous rocks (from the Latin word for fire) form when hot, molten rock crystallizes and solidifies. The melt originates deep within the Earth near active plate boundaries or hot spots, then rises toward the surface

Intrusive, or plutonic, igneous rock forms when magma is trapped deep inside the Earth. Some of the magma may feed volcanoes on the Earth’s surface, but most remains trapped below, where it cools very slowly over many thousands or millions of years until it solidifies

Extrusive, or volcanic, igneous rock is produced when magma exits and cools above (or very near) the Earth’s surface. These are the rocks that form at erupting volcanoes and oozing fissures

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igneous rock, any of various crystalline or glassy rocks formed by the cooling and solidification of molten earth material. Igneous rocks constitute one of the three principal classes of rocks, the others being metamorphic and sedimentary.

Earth is composed predominantly of a large mass of igneous rock with a very thin veneer of weathered material—namely, sedimentary rock. Whereas sedimentary rocks are produced by processes operating mainly at Earth’s surface by the disintegration of mostly older igneous rocks, igneous—and metamorphic—rocks are formed by internal processes that cannot be directly observed and that necessitate the use of physical-chemical arguments to deduce their origins

– Although Earth’s volcanic rocks have variable compositions, and contain many different elements, silicon and oxygen dominate most magmas.. – Petrologists generally report igneous rock compositions by listing oxide weight percentages

– At a fundamental level, we use the general terms ultramafic, mafic, intermediate, and silicic to describe rocks and magmas ranging from low silica-content to high silica-content. Silica content has a major effect on magma properties.

Silicic lavas are at the low end of this range, and mafic lavas at the high end.. – Magmas may contain up to 7 wt% volatiles, typically water vapor, carbon dioxide, and sulfur gases

Magma is a mixture of molten and semi-molten rock found beneath the surface of the Earth.. Earth Science, Geology, Geography, Physical Geography

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.. When magma is ejected by a volcano or other vent, the material is called lava

Magma is extremely hot—between 700° and 1,300° Celsius (1,292° and 2,372° Fahrenheit). This heat makes magma a very fluid and dynamic substance, able to create new landforms and engage physical and chemical transformations in a variety of different environments.

The Rock Cycle was probably the first of Earth’s cycles or systems to be recognized and studied, at least in a qualitative sense. It is presented in practically every introductory geology textbook as a sort of broad, all-encompassing framework for understanding the details of rocks and minerals — the traditional bread and butter of geology

Our goal here is to develop and then experiment with a model of the rock cycle.. In designing the system, it will help to refer to the figure of the rock cycle shown below.

So for instance, one kilogram of granite, a plutonic igneous rock, is broken down by variety of chemical and physical weathering processes when it is exposed and this kilogram of material then takes the form of sedimentary particles that commonly get transported away from the site of weathering to a final resting place where the are deposited and eventually form a kilogram of sedimentary rock. In reality, some of the starting kilogram is carried away in solution and ends up in the ocean where it will eventually be deposited, perhaps with the help of some organism, to form another kind of sedimentary rock

Magma (from Ancient Greek μάγμα (mágma) ‘thick unguent’)[1] is the molten or semi-molten natural material from which all igneous rocks are formed.[2] Magma (sometimes colloquially but incorrectly referred to as lava by laypeople) is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural satellites.[3] Besides molten rock, magma may also contain suspended crystals and gas bubbles.[4]. Magma is produced by melting of the mantle or the crust in various tectonic settings, which on Earth include subduction zones, continental rift zones,[5] mid-ocean ridges and hotspots

Following its ascent through the crust, magma may feed a volcano and be extruded as lava, or it may solidify underground to form an intrusion,[8] such as a dike, a sill, a laccolith, a pluton, or a batholith.[9]. While the study of magma has relied on observing magma after its transition into a lava flow, magma has been encountered in situ three times during geothermal drilling projects, twice in Iceland (see Use in energy production) and once in Hawaii.[10][11][12][13]

Most magma is rich in silica.[8] Rare nonsilicate magma can form by local melting of nonsilicate mineral deposits[16] or by separation of a magma into separate immiscible silicate and nonsilicate liquid phases.[17]. Silicate magmas are molten mixtures dominated by oxygen and silicon, the most abundant chemical elements in the Earth’s crust, with smaller quantities of aluminium, calcium, magnesium, iron, sodium, and potassium, and minor amounts of many other elements.[18] Petrologists routinely express the composition of a silicate magma in terms of the weight or molar mass fraction of the oxides of the major elements (other than oxygen) present in the magma.[19]

The microstructure and mineralogy of volcanic rocks is varied and complex, and their mechanical behaviour is similarly varied and complex. This review summarises recent developments in our understanding of the mechanical behaviour and failure modes of volcanic rocks

The presence of water, strain rate, and temperature can also influence uniaxial compressive strength. We also discuss the merits of micromechanical models in understanding the mechanical behaviour of volcanic rocks (which includes a review of the available fracture toughness data)

Differences between brittle and ductile mechanical behaviour (stress-strain curves and the evolution of porosity and acoustic emission activity) from triaxial deformation experiments are outlined. Brittle behaviour is typically characterised by shear fracture formation, and an increase in porosity and permeability

The following are suggested answers to the review questions at the end of chapters in Physical Geology. Answers to the exercises are provided in Appendix 3.

– Paleontology is an important aspect of geology and requires an understanding of biology, including evolution, the physiology of animals and plants and ecological relationships.. – Geologists provide information to reduce the risk of harm from hazards such as earthquakes, volcanoes, and slope failures; they play a critical role in the discovery of important resources; they contribute to our understanding of life and its evolution through paleontological studies; and they play a leading role in the investigation of climate change, past and present and its implications.

– A mineral has a specific chemical composition and lattice structure. Rocks are made out of minerals, and most rocks contain several different types of minerals.

This section looks at the relationship between plate tectonics, earthquakes and volcanoes, which helps to explain how volcanoes form.. If you look at a map showing the distribution of earthquakes around the world, it shows that they tend to be concentrated along well-defined belts

We can also can see from the distribution of volcanoes around the world that most lie on plate boundaries too, in particular a region a called the Pacific Ring of Fire around the edge of the Pacific Plate.. The tectonic plates are in contact with each other, but they are also moving relative to one another

It helps to explain this by looking at the three main types of plate boundary:. – constructive boundaries (divergent): where plates are moving away from each other as new crust is created between the two plates

Igneous rocks are “fire-born,” meaning that they are formed from the cooling and solidification of molten (melted) rock. The word igneous derives from ignis, the Latin word for “fire.” Molten rock material is known as magma until it is erupted onto the surface when it then is termed lava.

Intrusive igneous rocks are generally wholly crystalline and characterized by large crystal sizes visible to the naked eye because they cool slowly.. Many national parks were founded for their geology, and Yosemite is known throughout the world for its exceptional high cliffs and rounded domes

Extrusive igneous rocks are erupted onto the surface or into the atmosphere. Extrusive igneous rocks are also termed volcanic rocks—named for Vulcan, the Roman god of fire