Portal:Geology

Introduction

Earth seen from Moon

Earth science or geoscience includes all fields of natural science related to the planet Earth. This is a branch of science dealing with the physical constitution of the Earth and its atmosphere. Earth science is the study of our planet's physical characteristics, from earthquakes to raindrops, and floods to fossils. Earth science can be considered to be a branch of planetary science, but with a much older history. Earth science encompasses four main branches of study, the lithosphere, the hydrosphere, the atmosphere, and the biosphere, each of which is further broken down into more specialized fields.

There are both reductionist and holistic approaches to Earth sciences. It is also the study of Earth and its neighbors in space. Some Earth scientists use their knowledge of the planet to locate and develop energy and mineral resources. Others study the impact of human activity on Earth's environment, and design methods to protect the planet. Some use their knowledge about earth processes such as volcanoes, earthquakes, and hurricanes to plan communities that will not expose people to these dangerous events.

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Selected general articles

A geyser (/ˈɡaɪzər/, UK: /ˈɡiːzər/) is a spring characterized by intermittent discharge of water ejected turbulently and accompanied by steam. As a fairly rare phenomenon, the formation of geysers is due to particular hydrogeological conditions that exist only in a few places on Earth. Generally all geyser field sites are located near active volcanic areas, and the geyser effect is due to the proximity of magma. Generally, surface water works its way down to an average depth of around 2,000 metres (6,600 ft) where it contacts hot rocks. The resultant boiling of the pressurized water results in the geyser effect of hot water and steam spraying out of the geyser's surface vent (a hydrothermal explosion).

A geyser's eruptive activity may change or cease due to ongoing mineral deposition within the geyser plumbing, exchange of functions with nearby hot springs, earthquake influences, and human intervention. Like many other natural phenomena, geysers are not unique to planet Earth. Jet-like eruptions, often referred to as cryogeysers, have been observed on several of the moons of the outer solar system. Due to the low ambient pressures, these eruptions consist of vapor without liquid; they are made more easily visible by particles of dust and ice carried aloft by the gas. Water vapor jets have been observed near the south pole of Saturn's moon Enceladus, while nitrogen eruptions have been observed on Neptune's moon Triton. There are also signs of carbon dioxide eruptions from the southern polar ice cap of Mars. In the latter two cases, instead of being driven by geothermal energy, the eruptions seem to rely on solar heating via a solid-state greenhouse effect. Read more...
India map of climate classification.

The climate of India comprises a wide range of weather conditions across a vast geographic scale and varied topography, making generalisations difficult. Based on the Köppen system, India hosts six major climatic subtypes, ranging from arid deserts in the west, alpine tundra and glaciers in the north, and humid tropical regions supporting rainforests in the southwest and the island territories. Many regions have starkly different microclimates, making it one of the most climatically diverse countries in the world. The country's meteorological department follows the international standard of four climatological seasons with some local adjustments: winter( January and February), summer (March, April and May), a monsoon means rainy season (June to September), and a post-monsoon period (October to December).

India's geography and geology are climatically pivotal: the Thar Desert in the northwest and the Himalayas in the north work in tandem to effect a culturally and economically important monsoonal regime. As Earth's highest and most massive mountain range, the Himalayas bar the influx of frigid katabatic winds from the icy Tibetan Plateau and northerly Central Asia. Most of North India is thus kept warm or is only mildly chilly or cold during winter; the same thermal dam keeps most regions in India hot in summer. Read more...
Turquoise is an opaque, blue-to-green mineral that is a hydrated phosphate of copper and aluminium, with the chemical formula Cu Al₆(PO₄)₄(OH)₈·4H₂O. It is rare and valuable in finer grades and has been prized as a gemstone and ornamental stone for thousands of years owing to its unique hue. Like most other opaque gems, turquoise has been devalued by the introduction onto the market of treatments, imitations and synthetics.

The gemstone has been known by many names. Pliny the Elder referred to the mineral as callais (from Ancient Greek κάλαϊς) and the Aztecs knew it as chalchihuitl. The word turquoise dates to the 17th century and is derived from the French turquois meaning "Turkish" because the mineral was first brought to Europe through Turkey, from mines in the historical Khorasan of Persia. Read more...
Rain-obscured shot of the F3 tornado in Gallatin, Tennessee that killed seven people.

The tornado outbreak of April 6–8, 2006, was a major tornado outbreak in the central and parts of the southern United States that began on April 6, 2006, in the Great Plains and continued until April 8 in South Carolina, with most of the activity on April 7. The hardest-hit area was Middle Tennessee where several strong tornadoes devastated entire neighborhoods and left ten people dead. The worst damage took place in Gallatin, Tennessee. Other communities north of Nashville were also hard hit.

There were 73 tornadoes confirmed across 13 states, with the bulk of them coming on the afternoon and evening of April 7 across the South, particularly in Tennessee. In total, 10 deaths were reported as a result of the tornadoes, and over $650 million in damage was reported, of which over $630 million was in Middle Tennessee. It was the third major outbreak of 2006, occurring just days after another major outbreak on April 2. It was also considered to be the worst disaster event in Middle Tennessee since the Nashville Tornadoes of 1998 on April 16, 1998. Read more...
Geologic time represented in a diagram called a geological clock, showing the relative lengths of the eons of Earth's history and noting major events

The geological history of Earth follows the major events in Earth's past based on the geological time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the Solar System.

Earth was initially molten due to extreme volcanism and frequent collisions with other bodies. Eventually, the outer layer of the planet cooled to form a solid crust when water began accumulating in the atmosphere. The Moon formed soon afterwards, possibly as a result of the impact of a planetoid with the Earth. Outgassing and volcanic activity produced the primordial atmosphere. Condensing water vapor, augmented by ice delivered from comets, produced the oceans. Read more...
Cannikin warhead being lowered into test shaft

Amchitka (/æmˈtʃɪtkə/; Aleut: Amchixtax̂) is a volcanic, tectonically unstable island in the Rat Islands group of the Aleutian Islands in southwest Alaska. It is part of the Alaska Maritime National Wildlife Refuge. The island, with a land area of roughly 116 square miles (300 km²), is about 42 miles (68 km) long and 1 to 4 miles (1.6 to 6.4 km) wide. The area has a maritime climate, with many storms, and mostly overcast skies.

Amchitka was populated for more than 2,500 years by the Aleut people, but has had no permanent population since 1832. The island has been part of the United States since the Alaska Purchase of 1867. During World War II, it was used as an airfield by US forces in the Aleutian Islands Campaign. Read more...
Darwin, c. 1854, when he was preparing On the Origin of Species for publication

Charles Robert Darwin, (/ˈdɑːrwɪn/; 12 February 1809 – 19 April 1882) was an English naturalist, geologist and biologist, best known for his contributions to the science of evolution.[I] His proposition that all species of life have descended over time from common ancestors is now widely accepted, and considered a foundational concept in science. In a joint publication with Alfred Russel Wallace, he introduced his scientific theory that this branching pattern of evolution resulted from a process that he called natural selection, in which the struggle for existence has a similar effect to the artificial selection involved in selective breeding. Darwin has been described as one of the most influential figures in human history, and he was honoured by burial in Westminster Abbey.

Darwin published his theory of evolution with compelling evidence in his 1859 book On the Origin of Species. By the 1870s, the scientific community and a majority of the educated public had accepted evolution as a fact. However, many favoured competing explanations which gave only a minor role to natural selection, and it was not until the emergence of the modern evolutionary synthesis from the 1930s to the 1950s that a broad consensus developed in which natural selection was the basic mechanism of evolution. Darwin's scientific discovery is the unifying theory of the life sciences, explaining the diversity of life. Read more...
Average global temperatures from 2014 to 2018 compared to a baseline average from 1951 to 1980, according to NASA's Goddard Institute for Space Studies

Global warming is the long-term rise in the average temperature of the Earth's climate system. It is a major aspect of climate change and has been demonstrated by direct temperature measurements and by measurements of various effects of the warming. Global warming and climate change are often used interchangeably. But more accurately, global warming is the mainly human-caused increase in global surface temperatures and its projected continuation, while climate change includes both global warming and its effects, such as changes in precipitation. While there have been prehistoric periods of global warming, many observed changes since the mid-20th century have been unprecedented over decades to millennia.

The Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report concluded, "It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century". The largest human influence has been the emission of greenhouse gases such as carbon dioxide, methane, and nitrous oxide. Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 to 1.7 °C (0.5 to 3.1 °F) in a moderate scenario, or as much as 2.6 to 4.8 °C (4.7 to 8.6 °F) in an extreme scenario, depending on the rate of future greenhouse gas emissions and on climate feedback effects. These findings have been recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing. Read more...
Mahameru (Semeru) above Mount Bromo, East Java.

The geography of Indonesia is dominated by volcanoes that are formed due to subduction zones between the Eurasian plate and the Indo-Australian plate. Read more...
The Berlin Archaeopteryx specimen (A. siemensii).

Archaeopteryx (/ˌɑːrkiːˈɒptərɪks/, transl. 'old wing'; sometimes referred to by its German name Urvogel (transl. 'original bird' or 'first bird')), is a genus of bird-like dinosaurs that is transitional between non-avian feathered dinosaurs and modern birds. The name derives from the ancient Greek ἀρχαῖος (archaīos) meaning "ancient", and πτέρυξ (ptéryx), meaning "feather" or "wing". Between the late 19th century and the early 21st century, Archaeopteryx had been generally accepted by palaeontologists and popular reference books as the oldest known bird (member of the group Avialae). Older potential avialans have since been identified, including Anchiornis, Xiaotingia, and Aurornis.

Archaeopteryx lived in the Late Jurassic around 150 million years ago, in what is now southern Germany during a time when Europe was an archipelago of islands in a shallow warm tropical sea, much closer to the equator than it is now. Similar in size to a Eurasian magpie, with the largest individuals possibly attaining the size of a raven, the largest species of Archaeopteryx could grow to about 0.5 m (1 ft 8 in) in length. Despite their small size, broad wings, and inferred ability to fly or glide, Archaeopteryx had more in common with other small Mesozoic dinosaurs than with modern birds. In particular, they shared the following features with the dromaeosaurids and troodontids: jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second toes ("killing claw"), feathers (which also suggest warm-bloodedness), and various features of the skeleton. Read more...
Hurricane Isabel was the strongest Atlantic hurricane since Mitch, and the deadliest, costliest, and most intense hurricane in the 2003 Atlantic hurricane season. The ninth named storm, fifth hurricane, and second major hurricane of the season, Isabel formed near the Cape Verde Islands from a tropical wave on September 6, in the tropical Atlantic Ocean. It moved northwestward, and within an environment of light wind shear and warm waters, it steadily strengthened to reach peak winds of 165 mph (270 km/h) on September 11. After fluctuating in intensity for four days, during which it displayed annular characteristics, Isabel gradually weakened and made landfall on the Outer Banks of North Carolina, with winds of 105 mph (165 km/h) on September 18. Isabel quickly weakened over land and became extratropical over western Pennsylvania on the next day. On September 20, the extratropical remnants of Isabel were absorbed into another system over Eastern Canada.

In North Carolina, the storm surge from Isabel washed out a portion of Hatteras Island to form what was unofficially known as Isabel Inlet. Damage was greatest along the Outer Banks, where thousands of homes were damaged or even destroyed. The worst of the effects of Isabel occurred in Virginia, especially in the Hampton Roads area and along the shores of rivers as far west and north as Richmond and Baltimore. Virginia reported the most deaths and damage from the hurricane. About 64% of the damage and 69% of the deaths occurred in North Carolina and Virginia. Electric service was disrupted in areas of Virginia for several days, some more rural areas were without electricity for weeks, and local flooding caused thousands of dollars in damage. Read more...
The tectonic plates of the world were mapped in the second half of the 20th century.

Plate tectonics (from the Late Latin: tectonicus, from the Ancient Greek: τεκτονικός, lit. 'pertaining to building') is a scientific theory describing the large-scale motion of seven large plates and the movements of a larger number of smaller plates of the Earth's lithosphere, since tectonic processes began on Earth between 3.3 and 3.5 billion years ago. The model builds on the concept of continental drift, an idea developed during the first decades of the 20th century. The geoscientific community accepted plate-tectonic theory after seafloor spreading was validated in the late 1950s and early 1960s.

The lithosphere, which is the rigid outermost shell of a planet (the crust and upper mantle), is broken into tectonic plates. The Earth's lithosphere is composed of seven or eight major plates (depending on how they are defined) and many minor plates. Where the plates meet, their relative motion determines the type of boundary: convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries (or faults). The relative movement of the plates typically ranges from zero to 100 mm annually. Read more...
Yellowstone National Park is an American national park located mostly in Wyoming, with small sections in Montana and Idaho. It was established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872. Yellowstone was the first national park in the U.S. and is also widely held to be the first national park in the world. The park is known for its wildlife and its many geothermal features, especially Old Faithful geyser, one of its most popular features. It has many types of ecosystem, but the subalpine forest is the most abundant. It is part of the South Central Rockies forests ecoregion.

Native Americans have lived in the Yellowstone region for at least 11,000 years. Aside from visits by mountain men during the early-to-mid-19th century, organized exploration did not begin until the late 1860s. Management and control of the park originally fell under the jurisdiction of the Secretary of the Interior, the first being Columbus Delano. However, the U.S. Army was subsequently commissioned to oversee management of Yellowstone for a 30-year period between 1886 and 1916. In 1917, administration of the park was transferred to the National Park Service, which had been created the previous year. Hundreds of structures have been built and are protected for their architectural and historical significance, and researchers have examined more than a thousand archaeological sites. Read more...
The Ediacaran Period (/iː.diːˈæk.ə.rən/ ee-dee-AK-ə-rən), spans 94 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 541 Mya. It marks the end of the Proterozoic Eon, and the beginning of the Phanerozoic Eon. It is named after the Ediacara Hills of South Australia.

The Ediacaran Period's status as an official geological period was ratified in 2004 by the International Union of Geological Sciences (IUGS), making it the first new geological period declared in 120 years.
Although the period takes its name from the Ediacara Hills where geologist Reg Sprigg first discovered fossils of the eponymous Ediacara biota in 1946, the type section is located in the bed of the Enorama Creek within Brachina Gorge in the Flinders Ranges of South Australia, at . Read more...
Hurricane Lili was the second costliest, deadliest, and strongest hurricane of the 2002 Atlantic hurricane season, surpassing by Hurricane Isidore, which affected the same areas around a week before Lili. Lili was the twelfth named storm, fourth hurricane, and second major hurricane of the 2002 Atlantic hurricane season. The storm developed from a tropical disturbance in the open Atlantic on September 21. It continued westward, affecting the Lesser Antilles as a tropical storm, then entered the Caribbean. As it moved west, the storm dissipated while being affected by wind shear south of Cuba, and regenerated when the vertical wind shear weakened. It turned to the northwest and strengthened up to category 2 strength on October 1. Lili made two landfalls in western Cuba later that day, and then entered the Gulf of Mexico. The hurricane rapidly strengthened on October 2, reaching Category 4 strength that afternoon. It weakened rapidly thereafter, and hit Louisiana as a Category 1 hurricane on October 3. It moved inland and dissipated on October 6.

Lili caused extensive damage through the Caribbean, particularly to crops and poorly built homes. Mudslides were common on the more mountainous islands, particularly Haiti and Jamaica. In the United States, the storm cut off the production of oil within the Gulf of Mexico, and caused severe damage in parts of Louisiana. Lili was also responsible for severe damage to the barrier islands and marshes in the southern portion of the state. Total damage amounted to $925 million (2002 USD), and the storm killed 15 people during its existence. Read more...
Crater Lake (Klamath: giiwas) is a crater lake in south-central Oregon in the western United States. It is the main feature of Crater Lake National Park and is famous for its deep blue color and water clarity. The lake partly fills a nearly 2,148-foot (655 m)-deep caldera that was formed around 7,700 (± 150) years ago
by the collapse of the volcano Mount Mazama. There are no rivers flowing into or out of the lake; the evaporation is compensated for by rain and snowfall at a rate such that the total amount of water is replaced every 250 years. With a depth of 1,949 feet (594 m), the lake is the deepest in the United States. In the world, it ranks ninth for maximum depth, and third for mean (average) depth.

Crater Lake features two small islands. Wizard Island, located near the western shore of the lake, is a cinder cone approximately 316 acres (128 ha) in size. Phantom Ship, a natural rock pillar, is located near the southern shore. Read more...
Yosemite National Park (/joʊˈsɛmɪti/ yoh-SEM-i-tee) is an American national park located in the western Sierra Nevada of Central California, bounded on the southeast by Sierra National Forest and on the northwest by Stanislaus National Forest. The park is managed by the National Park Service and covers an area of 748,436 acres (1,169 sq mi; 3,029 km²) and sits in four counties: centered in Tuolumne and Mariposa, extending north and east to Mono and south to Madera County. Designated a World Heritage site in 1984, Yosemite is internationally recognized for its granite cliffs, waterfalls, clear streams, giant sequoia groves, lakes, mountains, meadows, glaciers, and biological diversity. Almost 95% of the park is designated wilderness.

On average, about four million people visit Yosemite each year, and most spend the majority of their time in the seven square miles (18 km²) of Yosemite Valley. The park set a visitation record in 2016, surpassing five million visitors for the first time in its history. Yosemite was central to the development of the national park idea. Galen Clark and others lobbied to protect Yosemite Valley from development, ultimately leading to President Abraham Lincoln's signing the Yosemite Grant in 1864. John Muir led a successful movement to have Congress establish a larger national park by 1890, one which encompassed the valley and its surrounding mountains and forests, paving the way for the National Park System. Read more...
Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space, especially the Sun and the Moon, which is Earth's only natural satellite. Earth orbits around the Sun in 365.256 days, a period known as an Earth sidereal year. During this time, Earth rotates about its axis about 366.256 times.

Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth. The gravitational interaction between Earth and the Moon causes tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest and most massive of the four rocky planets. Read more...
The inner planets. From left to right: Mercury, Venus, Earth, Mars and terrestrial dwarf planet, Ceres (sizes to scale)

The geology of solar terrestrial planets mainly deals with the geological aspects of the four terrestrial planets of the Solar System – Mercury, Venus, Earth, and Mars – and one terrestrial dwarf planet: Ceres. Earth is the only terrestrial planet known to have an active hydrosphere.

Terrestrial planets are substantially different from the giant planets, which might not have solid surfaces and are composed mostly of some combination of hydrogen, helium, and water existing in various physical states. Terrestrial planets have a compact, rocky surfaces, and Venus, Earth, and Mars each also have an atmosphere. Their size, radius, and density are all similar. Read more...
Hurricane Gloria was the first significant tropical cyclone to strike the northeastern United States since Hurricane Agnes in 1972 and the first major storm to affect New York and Long Island directly since Hurricane Donna in 1960. It was a powerful Cape Verde hurricane that formed during the 1985 Atlantic hurricane season, originating from a tropical wave on September 16 in the eastern Atlantic Ocean. After remaining a weak tropical cyclone for several days, Gloria intensified into a hurricane on September 22 north of the Lesser Antilles. During that time, the storm had moved generally westward, although it turned to the northwest due to a weakening of the ridge. Gloria quickly intensified on September 24, and the next day reached peak winds of 145 mph (230 km/h). The hurricane weakened before striking the Outer Banks of North Carolina on September 27. Later that day, Gloria made two subsequent landfalls on Long Island and across the coastline of western Connecticut, before becoming extratropical on September 28 over New England. The remnants moved through Atlantic Canada, eventually dissipating on October 2.

Before Gloria made landfall, the National Hurricane Center issued hurricane warnings at some point for the East Coast of the United States from South Carolina to Maine. Hundreds of thousands of people evacuated, and the hurricane was described as the "storm of the century". In general, Gloria's strongest winds remained east of the center, which largely spared locations from North Carolina to New Jersey, and the passage at low tide reduced storm surge. Hurricane-force winds and gusts affected much of the path, which knocked down trees and power lines. This left over 4 million people without power, including the worst power outage in Connecticut history related to a natural disaster. The extended power outage on Long Island, affecting 1.5 million people at some point, caused the Long Island Lighting Company to be shut down and be replaced with a public company. Fallen trees caused six of the storm's fourteen deaths. Read more...
An artist's rendering of an asteroid a few kilometers across colliding with the Earth. Such an impact can release the equivalent energy of several million nuclear weapons detonating simultaneously.

The Cretaceous–Paleogene (K–Pg) extinction event, also known as the Cretaceous–Tertiary (K–T) extinction, was a sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago. With the exception of some ectothermic species such as the leatherback sea turtle and crocodiles, no tetrapods weighing more than 25 kilograms (55 pounds) survived. It marked the end of the Cretaceous period, and with it the end of the entire Mesozoic Era, opening the Cenozoic Era that continues today.

In the geologic record, the K–Pg event is marked by a thin layer of sediment called the K–Pg boundary, which can be found throughout the world in marine and terrestrial rocks. The boundary clay shows high levels of the metal iridium, which is rare in the Earth's crust, but abundant in asteroids. Read more...
Mary Anning with her dog, Tray, painted before 1842; the Golden Cap outcrop can be seen in the background

Mary Anning (21 May 1799 – 9 March 1847) was an English fossil collector, dealer, and palaeontologist who became known around the world for important finds she made in Jurassic marine fossil beds in the cliffs along the English Channel at Lyme Regis in the county of Dorset in Southwest England. Her findings contributed to important changes in scientific thinking about prehistoric life and the history of the Earth.

Anning searched for fossils in the area's Blue Lias cliffs, particularly during the winter months when landslides exposed new fossils that had to be collected quickly before they were lost to the sea. She nearly died in 1833 during a landslide that killed her dog, Tray. Her discoveries included the first ichthyosaur skeleton correctly identified; the first two more complete plesiosaur skeletons found; the first pterosaur skeleton located outside Germany; and important fish fossils. Her observations played a key role in the discovery that coprolites, known as bezoar stones at the time, were fossilised faeces. She also discovered that belemnite fossils contained fossilised ink sacs like those of modern cephalopods. When geologist Henry De la Beche painted Duria Antiquior, the first widely circulated pictorial representation of a scene from prehistoric life derived from fossil reconstructions, he based it largely on fossils Anning had found, and sold prints of it for her benefit. Read more...
The Chicxulub crater (/ˈtʃiːkʃʊluːb/; Mayan: [tʃʼikʃuluɓ]) is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located near the town of Chicxulub, after which the crater is named. It was formed by a large asteroid or comet about 11 to 81 kilometers (6.8 to 50.3 miles) in diameter, the Chicxulub impactor, striking the Earth. The date of the impact coincides precisely with the Cretaceous–Paleogene boundary (commonly known as the "K–Pg boundary"), slightly less than 66 million years ago, and a widely accepted theory is that worldwide climate disruption from the event was the cause of the Cretaceous–Paleogene extinction event, a mass extinction in which 75% of plant and animal species on Earth became extinct, including all non-avian dinosaurs.

The crater is estimated to be 150 kilometers (93 miles) in diameter and 20 kilometers (12 miles) in depth, well into the continental crust of the region of about 10–30 kilometers (6.2–18.6 miles) depth. It is the second largest confirmed impact structure on Earth, and the only one whose peak ring is intact and directly accessible for scientific research. Read more...

Did you know ...?

... that New Zealand geologist Patrick Marshall (pictured) was the first who used the term "andesite line"?
...that the Earth's magnetic field is shaped roughly as a magnetic dipole, with the poles currently located proximate to the planet's geographic poles?
...In total, about 401 people have been outside the Earth's atmosphere as of 2004, and, of these, twelve have walked on the Moon?
...that the Apache-Sitgreaves National Forest is a 2 million acre (8000 km²) national forest which runs along the Mogollon Rim and the White Mountains in east-central Arizona and extending into New Mexico, United States?
...that the Himalaya mountain range is the world's highest mountain range?
... that the 1999 Chamoli earthquake in India, in which 103 people died, was also felt in the Baitadi, Dadeldhura and Kanchanpur districts in Nepal?

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Selected images

Incandescent Pahoeoe Fountain at Shield volcano, by J.D. Griggs, USGS
Weathered rocks at Joshua Tree National Park, by Mila Zinkova
Mount Redoubt eruption, by R. Clucas (USGS) (edited by Janke)
A 2002 eruption of Mount Etna, a volcano on the Italian island of Sicily, viewed from the International Space Station. (Credit: NASA, with image edits by User:Darkone.)
Winter is one of the four seasons of temperate zones. Meteorological winter is the season having the shortest days (which vary greatly according to latitude) and the lowest temperatures. (Credit: Richard Fabi.)
Sarychev Peak at Explosive eruption, by NASA
Hurricane Katrina was the third most powerful storm of the 2005 Atlantic hurricane season. It first made landfall as a Category 1 hurricane just north of Miami, Florida on August 25, 2005, then again on August 29 along the Central Gulf Coast near Buras-Triumph, Louisiana as a Category 4 storm. This photograph of the eye of the hurricane was taken from a NOAA Hurricane Hunter aircraft on August 28, 2005. (Credit: NOAA.)
Mount Hood reflected in Mirror Lake, Oregon. (Credit: Oregon's Mt. Hood Territory.)
Pyrite, by JJ Harrison
Concretions, by Mbz1
Ant trapped in Baltic amber, by Baltic-amber-beetle (edited by AmericanXplorer13)
Antarctica, the continent surrounding the Earth's South Pole, is the coldest place on earth and is almost entirely covered by ice. Antarctica was discovered in late January 1820. Too cold and dry to support virtually any vascular plants, Antarctica's flora presently consists of around 250 lichens, 100 mosses, 25-30 liverworts, and around 700 terrestrial and aquatic algal species. (Credit: NASA.)
Azurite, by JJ Harrison
An October 2002 eruption of Mount Etna, a volcano on the Italian island of Sicily, as seen from the International Space Station. Etna is the largest of Italy's three active volcanoes and one of the most active in the whole entire world. This eruption, one of Etna's most vigorous in years, was triggered by a series of earthquakes. Ashfall was reported as far away as Libya, 600 km (373 mi) to the south. (Credit: Expedition 5 crew.)
This map shows the tracks of all tropical cyclones that formed worldwide from 1985 to 2005. The points show the locations of the storms at six-hourly intervals and use the color scheme shown on the right from the Saffir-Simpson Hurricane Scale. (Credit: Nilfanion.)
Opal, by JJ Harrison
Diatomaceous earth, by Richard Wheeler
Petrified wood, by Daniel Schwen
Creedite, by JJ Harrison
Dundasite by JJ Harrison
Thin section scan, by Kallerna
Cinnabar, by JJ Harrison
Volcanic tephra, by Godot13
Gypsum, by JJ Harrison
Petrified log at Petrified Forest National Park, by Moondigger
A true-color picture of Ireland, as seen from space, with the Atlantic Ocean to the west and the Irish Sea to the east.
Platinum, by Alchemist-hp
Erg Chebbi (Arabic: عرج شبّي‎) is the sole Saharan erg in Morocco. It is 22 km long (North-South) and 5 km wide. Its dunes reach a maximum height of 150 meters. It is located roughly 40 kilometers south-east of Erfoud. The local center for tourists is the village of Merzouga. (Credit: Rosa Cabecinhas and Alcino Cunha.)
Crocoite, by JJ Harrison
Atmospheric gases scatter blue wavelengths of visible light more than other wavelengths, giving the Earth’s visible edge a blue halo. At higher and higher altitudes, the atmosphere becomes so thin that it essentially ceases to exist. Gradually, the atmospheric halo fades into the blackness of space. (Credit: NASA's Earth Observatory.)
Erosion of the bluff in Pacifica, by mbz1
Tsunami in Thailand at 2004 Indian Ocean earthquake and tsunami, by David Rydevik
Cirrus clouds are composed of ice crystals and shaped like hairlike filaments. They are formed at an altitudes above 5000 metres (16,500 feet). The streaks are made of snowflakes that are falling from the cloud and being caught by the high level winds. The streaks point in the direction of the wind and may appear straight giving the clouds the appearance of a comma (cirrus uncinus), or may by seem tangled, an indication of high level turbulence. (Credit: Piccolo Namek.)
A thunderstorm is a form of severe weather involving lightning and thunder. Thunderstorms have had a lasting and powerful influence on mankind. Romans thought them to be battles waged by Jupiter. Thunderstorms were associated with the Thunderbird, held by Native Americans to be a servant of the Great Spirit. (Credit: John Kerstholt.)
2004 Indian Ocean Earthquake tsunami at 2004 Indian Ocean earthquake and tsunami, by Vasily V. Titov, NOAA (edited by Veledan)
Specimen from a palaeontological site of Lebanon, by Mila Zinkova
Northern shore meadows of Sihlsee, an artificial lake near Einsiedeln in the Canton of Schwyz, Switzerland. (Credit: Markus Bernet.)
Pressure release of granite in the Enchanted Rock State Natural Area of Texas, United States. The photo shows the geological exfoliation of granite dome rock. (Taken by Wing-Chi Poon on 2nd April 2005.)
Malachite, by JJ Harrison
Sandstone, by Moondigger
Glacier retreat is a type of glacial motion in which more material ablates from its terminus of the glacier than is replenished by flow into that region. In this region of the Bhutan-Himalaya, glacial lakes have been rapidly forming on the surface of the debris-covered glaciers and researchers have found a strong correlation between increasing temperatures and glacial retreat. (Credit: NASA & USGS.)
Smoky quartz, by JJ Harrison
Amethyst, by JJ Harrison
The Richat Structure is a depression in the country of Mauritania, almost 50 km (30 mi) across. It was originally thought to be the impact of a meteorite. Now it is thought to be a symmetrical uplift (circular anticline or dome) that has been exposed to erosion. In this false-color photo, bedrock is brown, sand is yellow and white, vegetation is green, and salty sediments are blue. (Credit: Landsat 7.)
Astronauts aboard the Space Shuttle Discovery recorded this rarely seen phenomenon of the full Moon partially obscured by the atmosphere of Earth. The image was recorded with an electronic still camera at 15:15:15 GMT, Dec. 21, 1999. (Credit: NASA.)
Satellite image of Cyclone Gafilo, a powerful Category 5 tropical cyclone which struck Madagascar in March 2004, causing devastating damage. This was taken just before landfall, when the system was at its peak intensity about 333 km (207 mi) east of Madagascar, with sustained windspeed of 260 km/h (160 mph). At least 250 people were listed dead, with more missing, and 300,000 people were left homeless due to Gafilo. (Credit: Terra satellite, NASA.)
Crystalline dolomite and magnesite, by Didier Descouens
Oceans cover almost three quarters (71%) of the surface of the Earth, and nearly half of the world's marine waters are over 3000 m deep. This global, interconnected body of salt water, called the World Ocean, is divided by the continents and archipelagos into the following five bodies, from the largest to the smallest: the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean, and the Arctic Ocean. Official boundaries are defined by the International Hydrographic Organization. (Credit: Alexandre Van de Sande.)
The world's largest compass rose, drawn on the desert floor at Edwards Air Force Base in California, United States. Painted on the playa near Dryden Flight Research Center, it is inclined to magnetic north and is used by pilots for calibrating heading indicators. (Credit: NASA.)
Cassiterite, by Alchemist-hp
Wulfenite, by Didier Descouens
Quartz, by JJ Harrison

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In the news

28 January 2020 – 2020 Caribbean earthquake: A magnitude 7.7 earthquake is recorded off the coast of Jamaica. (KRON 4 News)
24 January 2020 – 2020 Elazığ earthquake: At least 36 are killed and more than 1,600 injured in an earthquake centered near Elazığ in Eastern Anatolia. (BBC)
17 January 2020 – Sea level rise driven by effects of global warming on oceans: Foreign Minister of the Maldives Abdulla Shahid says that his country could lose entire islands unless it can access cheap financing to fight climate change. (Reuters)
13 January 2020 – Presolar grains: Analysis of a meteorite found in Australia in 1969 reveals stardust formed 5 to 7 billion years ago, older than Earth's 4.6 billion year-old sun, making the meteor and its stardust the oldest solid material ever discovered on Earth. (MSN)
8 January 2020 – List of fast radio bursts: Scientists announce through the journal Nature the discovery of a repeating fast radio burst known as FRB 180916 coming from a nearby spiral galaxy around 500 million light years from Earth. It is the second repeating FRB to have been localized. (The Independent)
7 January 2020 –: A magnitude 6.4 earthquake strikes Puerto Rico, killing one and injuring nine others (NBC)

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