Igneous Rocks Quiz



9 Questions

What are igneous rocks formed through?

What can magma be derived from?

What percentage of the top 16 kilometers of the Earth's crust by volume is made up of igneous and metamorphic rocks?

What is the difference between intrusive and extrusive igneous rocks?

What is the volume of extrusive rock erupted annually by volcanoes related to?

What are igneous rocks classified according to?

What is the role of water in magma formation?

What is the most typical mechanism for the formation of magma within continental crust?

What are most magmas composed of?


Igneous Rocks: A Detailed Overview

  • Igneous rocks are formed through the cooling and solidification of magma or lava.

  • Magma can be derived from partial melts of existing rocks in either the mantle or crust of a planet.

  • Igneous rocks occur in a wide range of geological settings, including shields, platforms, orogens, basins, large igneous provinces, extended crust, and oceanic crust.

  • Igneous and metamorphic rocks make up 90-95% of the top 16 kilometres of the Earth's crust by volume.

  • Igneous rocks can be either intrusive or extrusive.

  • Intrusive rocks are formed from magma that cools and solidifies within the crust of a planet, while extrusive rocks are formed by the cooling of molten magma on the Earth's surface.

  • The central cores of major mountain ranges consist of intrusive igneous rocks.

  • The molten rock, which typically contains suspended crystals and dissolved gases, is called magma. When magma reaches the surface, it is called lava.

  • The volume of extrusive rock erupted annually by volcanoes varies with plate tectonic setting.

  • Igneous rocks are classified according to mode of occurrence, texture, mineralogy, chemical composition, and the geometry of the igneous body.

  • Texture refers to the size, shape, and arrangement of the mineral grains or crystals of which the rock is composed.

  • The chemistry of igneous rocks is expressed differently for major and minor elements and for trace elements.Classification and Origin of Igneous Rocks

  • There are three main magma series: tholeiitic, calc-alkaline, and alkaline.

  • These magma series occur in various plate tectonic settings, such as mid-ocean ridges, back-arc basins, oceanic islands, island arcs, and continental large igneous provinces.

  • The distribution of these magma series is related to depth and the age of the subduction zone.

  • The classification of igneous rocks was based on the geological age and occurrence of the rocks until the 20th century.

  • In 1902, a "quantitative" classification based on chemical analysis was proposed by Charles Whitman Cross, Joseph P. Iddings, Louis V. Pirsson, and Henry Stephens Washington.

  • The concept of normative mineralogy, introduced by Cross and his coinvestigators, has endured and inspired a flurry of new classification schemes.

  • By 1989, a single system of classification had been agreed upon, which was further revised in 2005.

  • The Earth's crust averages about 35 kilometers thick under the continents and only 7-10 kilometers beneath the oceans.

  • Rocks may melt due to a decrease in pressure, change in composition, increase in temperature, or a combination of these processes.

  • Water lowers the solidus temperature of rocks at a given pressure, while carbon dioxide has a relatively less important role in magma formation.

  • Increase in temperature is the most typical mechanism for the formation of magma within continental crust.

  • Most magmas are mixes of melt, crystals, and sometimes gas bubbles, and they can separate as magmas evolve.


Test your knowledge on the fascinating world of igneous rocks with this detailed overview quiz! From the formation of magma and lava to the classification and origin of igneous rocks, this quiz covers it all. Challenge yourself to identify the different types of igneous rocks based on their texture, mineralogy, and chemical composition. Whether you're a geology enthusiast or simply curious about the Earth's crust, this quiz is a must-try. Take the quiz now and see how much you know about igneous

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