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Geology: Most Popular ArticlesThese articles are the most popular over the last month. Rock Picture Gallery Pictures and descriptions of rocks on About.com Geology Rock Identification Tables Three tables cover 37 of the most common rock types, with simple ways to distinguish them. Mineral Picture Gallery The mineral wing of the About Geology Picture Gallery. About Igneous Rocks The three great rock classes--igneous, sedimentary and metamorphic--are introduced with igneous rocks. Granite Granite exemplified by a salt-and-pepper specimen from central California. Sandstone A large boulder of sandstone, with visible layering features, sits in a Berkeley landscaping yard. Basalt Basalt from Hawaii with vesicles and olivine grains. About Sedimentary Rocks The second of the three great rock classes is introduced with photos. Limestone Limestone appears in a New York roadcut. Obsidian Obsidian chunk from the Napa Valley volcanoes. Landform Picture Gallery The landform wing of the About Geology Picture Gallery. The Richter Scales Nowadays, every earthquake magnitude scale is the Richter scale. Slate Slate sits in a stoneyard. Seismic Hazard Map, China The China part of the Global Seismic Hazard Map of 1999. Plate Tectonics - The World's Crustal Plates The Earth's crustal plates, from the U.S. Geological Survey About Metamorphic Rocks The three great rock classes--igneous, sedimentary and metamorphic--are introduced with photos, finishing with metamorphic. About the Earth's Core How we study the Earth's core and what it's made of. Fossil Picture Gallery Pictures of fossils in the About Geology Picture Gallery. Gabbro Gabbro is the plutonic equivalent of basalt. Schist Schist is a metamorphic rock that comes in many varieties. About the San Andreas Fault Home page for everything about the San Andreas fault. The Mohs Scale of Relative Mineral Hardness The ten-mineral Mohs scale of relative hardness, based on what scratches what. Andesite Andesite from the Sutter Buttes, California. Chert Chert pebbles from California. Quartzite A boulder of tough, solid quartzite sits by a Las Vegas building. About Quartz Quartz alone and in rocks, with some notes. Glacier Picture Gallery Pictures of glacial features and the processes of glaciers. Geologic Map of California California geologic map, at four different scales. Shale Shale or mudstone forms on the sea floor. Global Seismic Hazard Map Index First page of the Global Seismic Hazard Map gallery. Aa Lava A glowing flow of aa lava advances from the Puu Oo eruption on Hawaii island. Diorite Diorite is a plutonic rock, like granite without quartz. Gneiss A fresh boulder of meat-colored Pinto Gneiss, in Joshua Tree National Park, shows the characteristics of this metamorphic rock type. Pictures of Geologic Features and Processes Pictures of geologic features and the processes of geology. Pumice Pumice from a Californian volcano. Agate Agate is the name for the best quality of chert. Geologic Map of Texas Texas geologic map, courtesy of the state bureau of economic geology Serpentinite Serpentinite, the California state rock, at the Oakland Museum of California. Gems to Minerals, Minerals to Gems Mineral names and their corresponding gem names. Felsite Felsite is the extrusive equivalent of granite. Marble Marble is metamorphosed limestone. 1906 San Francisco Earthquake The Great San Francisco Earthquake was the stuff of legend, but it really happened. Siltstone Siltstone, like sandstone but much finer grained. Scoria Scoria from a Californian volcano. Porphyry Porphyry is a widely varying type of igneous rock. What Is Geology? The whole of Earth sciences, compressed to a nutshell. Conglomerate Conglomerate is a sign of a vigorous environment. Phyllite Photo of phyllite showing its micaceous sheen. The Tibetan Plateau The largest highest place on Earth is a showcase of plate tectonics. Tuff Tuff forms a cliff of tierra blanca in El Salvador. Coal Coal is fossil peat. Amphibolite Amphibolite is metamorphosed basaltic rock. Syenite Hand specimen of syenite. Pegmatite Pegmatite in a Colorado boulder. Breccia Breccia takes many forms; this photo shows a pebble of a fault breccia. Dolomite Rock A chunk of coarsely crystalline dolomite. Rock Gypsum Rock gypsum from a Nevada roadside. Pyroxenite Pyroxenite from the Feather River Ultramafics of the northern Sierra Nevada. About the Earth's Mantle A look at six different aspects of the Earth's mantle. Migmatite Migmatite is highly metamorphosed rock. Rhyolite Rhyolite from the Sutter Buttes, California. Gypsum Clear specimens and desert roses composed of gypsum. Coquina Coquina is a sedimentary rock made of shell fragments. What Is a Rock? Everyone knows what a rock is, until you ask what it is exactly. Solar Studies Studying the Sun tells a lot about the Earth. Thunder Egg Thunder eggs form in volcanic sediments. Inside is solid agate. Plate Tectonics in a Nutshell A simple starting point for the basics of plate tectonics. Wacke or Graywacke Wacke or graywacke is a sloppy kind of sandstone. Mountain Pictures - California Peaks Great pictures of great Californian mountains. Stop 5, the Glory Hole An overflow structure helps drain Lake Berryessa in northern California. Granodiorite A polished slab of granodiorite from southeastern New Hampshire. Arkose Arkose from the Fountain Formation of Colorado. Eclogite Eclogite, an extreme metamorphic rock from the mantle. Fault Types in a Nutshell The three basic types of fault, with their nomenclature, in a nutshell. Deaths from Tsunamis, by Ocean The deadliest tsunamis recorded in each ocean basin. The Biggest Eruptions The biggest eruptions in history and prehistory About Tsunamis Tsunamis or tidal waves--whatever you call them, watch out. Tectonic Plate Boundaries, Eastern Hemisphere Plate boundaries of the Eastern Hemisphere: divergent, convergent, and transform. Pahoehoe Lava A flow of fresh hot pahoehoe lava smothers an old Hawaiian footpath. Earth Formation in a Nutshell The straight story of how Earth began, as today's geologists tell it. Banded Iron Formation Australian 'folded tiger iron' is a spectacular variety of banded iron formation. Muscovite Muscovite or white mica, a nice hand specimen from New York state. Recipes for Volcanoes Moviemakers and scientists have gone beyond vinegar and baking soda. The Tokai Earthquake of 20xx Japan has been preparing for it for over 25 years. Geologic Map of Alabama Alabama geologic map, courtesy of the state geological survey Plagioclase Feldspar Plagioclase feldspar is a major rock-forming mineral. Calcite Photo of Iceland spar calcite rhomb showing double refraction, with notes. Mount St. Helens Eruption Remembering a scientist who died in the 1980 eruption of Mount St. Helens. Bre-X Gold Scandal First there is a mountain of gold, then there is no mountain, then there is no gold mining company named Bre-X. Articles on Earthquakes Features about earthquakes, seismology, and related phenomena from your About Geology Guide. Tectonic Plates with Topography, Eastern Hemisphere Topography of the Eastern Hemisphere with tectonic plate boundaries. Lapilli Tuff Lapilli tuff in a California outcrop. Earthquake Statistics A graph displays the numbers of quakes of different magnitudes. Alabaster An image of alabaster, or fine-grained travertine. Geodes (Before) Two small unbroken geodes offer the promise of glittering guts. Greenstone Greenstone in a California roadcut and outcrop. Blueschist Blueschist, close up and deployed in a decorative setting. Potassium or Alkali Feldspar - Microcline (Amazonite) Bright-green amazonite is an easy-to-recognize variety of microcline, a potassium or alkali feldspar. Chalcedony Chalcedony is the microcrystalline form of quartz. Lisbon Earthquake, 1 November 1755 Lisbon earthquake of 1 November 1755, images and notes. Geologic Map of New York New York geologic map, presented at four different scales. Geologic Map of Colorado The great USGS Colorado geologic map, presented at full size. Geologic Time Scale: The Cenozoic Era Ages, epochs and periods of the Cenozoic Era, part of the geologic time scale. Greenschist Greenschist, a dark-green silicate rock formed by metamorphism of old seafloor. Magnetite Magnetite--a genuine lodestone up close. Zen Rock Garden A quiet zen rock garden suggests a landscape with the simplest means. Peat Peat is the precursor of coal. Actinolite Actinolite, a green silicate mineral formed by the metamorphism of old seafloor. Alluvial Fan A wide alluvial fan debouches from a range in Montana. The Global Seismic Hazard Map The first map to show the entire world's seismic hazard consistently is out--and it's all here on this site. Talc Talc, the softest mineral. Asphalt Asphalt from the McKittrick oil seep. Geologic Time Scale: Eons and Eras The three eons and ten eras of the geologic time scale. Graphite - Graphite Specimen Graphite in its raw form. Diamond - Natural Diamond Specimen A natural diamond grain from Congo shows rough crystal faces. Olivine Olivine grain in Kilauea basalt. Fulgurite A small Moroccan fulgurite records a lightning strike on sand. Dolomite Closeup of granular dolomite. Mercalli Earthquake Intensity Scale The modified Mercalli intensity scale rates the impact of quakes from I to XII. Biotite Biotite is black mica, a common rock-forming mineral. Geology Wallpaper Images - Rock Closeups A selection of wallpaper images of rocks in loving detail. Travertine Travertine, a low-density form of limestone. Brachiopod A typical brachiopod fossil. Geologic Map of Chile Geologic map of Chile. Halite Halite in three forms: rock salt, halite crystals and table salt. Valley Glacier - or Mountain or Alpine Glacier Bucher Glacier, a typical valley - or mountain or alpine - glacier. Kettle Kettles dot the outwash plain of Bering Glacier in Alaska. How to Identify Minerals First steps in mineral identification. Geologic Map of Michigan Bedrock geologic map of Michigan, at three different scales, courtesy of the state of Michigan What Is a Mineral? Minerals meet four criteria, more or less strict. Pyrite Pyrite grains and crystals in many settings. Mica Schist A dark mica schist from Manhattan. Geologic Map of Washington State Washington state geologic map, at three different scales, presented with notes. Earthquake Intensities Intensity scales measure how bad a quake is, on a scale from I to XII. Geologic Time Scale: Precambrian Time The Precambrian part of the geologic time scale. Gold Nugget Gold nugget, in the gallery of minerals with metallic luster. Conflict Diamonds The problem of clandestine gems has no geological solution. Geologic Map of New Mexico New Mexico geologic map, courtesy of the New Mexico Bureau of Mines and Mineral Resources Geology Desktop Wallpaper Pictures Free 800x600, 1024x768 and 1280x1024 geology pictures for your computer's desktop wallpaper. "Herkimer Diamond" Quartz Crystal Herkimer diamonds, the special double-ended stones from upstate New York. What Are Fossils? Fossils are precious gifts from the geologic past. Ruby - Mineral Specimen of Ruby A ruby pebble from India. Geologic Map of Arkansas Arkansas geologic map, presented at four different scales with notes. Sumatra 26 Dec 2004 M9.3 The greatest earthquake in 40 years killed 300,000 people. Earthquake Lights A new theory of earthquake lights looks promising Geologic Map of Georgia Georgia geologic map, at three different scales, created from the USGS data. Anticline Anticline. Geologic Map of Alaska Alaska geologic map, at three different scales. Chondrite Meteorite Chondrites are the most common kind of meteorite. Amethyst Amethyst, the purple variety of quartz, is shown here as a geode crust. |
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