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  2. Geode - Wikipedia

    en.wikipedia.org/wiki/Geode

    Geode. A geode (/ ˈdʒiː.oʊd /; from Ancient Greek γεώδης (geṓdēs) 'earthlike') is a geological secondary formation within sedimentary and volcanic rocks. Geodes are hollow, vaguely spherical rocks, in which masses of mineral matter (which may include crystals) are secluded. The crystals are formed by the filling of vesicles in ...

  3. Thunderegg - Wikipedia

    en.wikipedia.org/wiki/Thunderegg

    A geode is a simple term for a rock with a hollow in it, often with crystal formation/growth. A thunderegg on the other hand is a specific geological structure. A thunderegg may be referred to as a geode if it has a hollow in it, but not all geodes are thundereggs because there are many different ways for a hollow to form.

  4. List of rock formations - Wikipedia

    en.wikipedia.org/wiki/List_of_rock_formations

    Rock formations in Ongamira Valley, Sierras de Córdoba, Argentina. Belogradchik Rocks, Balkan Mountains, Bulgaria. "Jaws", an erosional fin in Little Finland, Nevada, US. "Hajdučka vrata" on Čvrsnica, Herzegovina. Paklenica, Croatia. Devil's Town, Serbia. Three Sisters in Blue Mountains, Australia. A rock formation is an isolated, scenic, or ...

  5. Glossary of landforms - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_landforms

    Limestone pavement – Natural karst landform consisting of a flat, incised surface of exposed limestone. Mesa – Elevated area of land with a flat top and sides, usually much wider than buttes. Mushroom rock – Naturally occurring rock whose shape resembles a mushroom. Natural arch – Arch-shaped natural rock formation.

  6. Caldera - Wikipedia

    en.wikipedia.org/wiki/Caldera

    Caldera. A caldera (/ kɔːlˈdɛrə, kæl -/ [1] kawl-DERR-ə, kal-) is a large cauldron -like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the structural integrity of such a chamber, greatly ...

  7. Volcanic rock - Wikipedia

    en.wikipedia.org/wiki/Volcanic_rock

    Volcanic rock. Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks.

  8. List of rock types - Wikipedia

    en.wikipedia.org/wiki/List_of_rock_types

    Claystone – Clastic sedimentary rock composed primarily of clay-sized particles. Coal – Combustible sedimentary rock composed primarily of carbon. Conglomerate – Sedimentary rock composed of smaller rock fragments. Coquina – Sedimentary rock that is composed mostly of fragments of shells.

  9. Karst - Wikipedia

    en.wikipedia.org/wiki/Karst

    Global distribution of major outcrops of carbonate rocks (mainly limestone, except evaporites). The English word karst was borrowed from German Karst in the late 19th century, [6] which entered German usage much earlier, [7] to describe a number of geological, geomorphological, and hydrological features found within the range of the Dinaric Alps, stretching from the northeastern corner of ...