Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also include the study of the solid features of any terrestrial planet or natural satellite such as Mars or the Moon. Modern geology significantly overlaps all other earth sciences, including hydrology and the atmospheric sciences, and so is treated as one major aspect of integrated earth system science and planetary science.
Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a common rock, is a combination of the minerals quartz, feldspar and biotite. The Earth's outer solid layer, the lithosphere, is made of rock.
Geochronology is the science of determining the age of rocks, fossils, and sediments using signatures inherent in the rocks themselves. Absolute geochronology can be accomplished through radioactive isotopes, whereas relative geochronology is provided by tools such as palaeomagnetism and stable isotope ratios. By combining multiple geochronological indicators the precision of the recovered age can be improved.
The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lithology may refer to either a detailed description of these characteristics, or a summary of the gross physical character of a rock. Lithology is the basis of subdividing rock sequences into individual lithostratigraphic units for the purposes of mapping and correlation between areas. In certain applications, such as site investigations, lithology is described using a standard terminology such as in the European geotechnical standard Eurocode 7.
The Vredefort crater is the largest verified impact crater on Earth, more than 300 kilometres (190 mi) across when it was formed. What remains of it is located in the present-day Free State province of South Africa and named after the town of Vredefort, which is situated near its centre. Although the crater itself has long since eroded away, the remaining geological structures at its centre are known as the Vredefort Dome or Vredefort impact structure. The crater is estimated to be 2.023 billion years old, with impact being in the Paleoproterozoic Era. It is the second-oldest-known crater on Earth.
A formation or geological formation is the fundamental unit of lithostratigraphy. A formation consists of a certain amount of rock strata that have a comparable lithology, facies or other similar properties. Formations are not defined by the thickness of their rock strata; therefore the thickness of different formations can vary widely.
Kasha-Katuwe Tent Rocks National Monument is a U.S. National Monument located approximately 40 miles southwest of Santa Fe, New Mexico, near Cochiti Pueblo. Managed by the Bureau of Land Management (BLM), it was established as a U.S. National Monument by President Bill Clinton in January 2001. Kasha-Katuwe means "white cliffs" in the Pueblo language Keresan. The monument is a unit of the BLM's National Conservation Lands.
Vasquez Rocks Natural Area Park is a 932-acre (377-hectare) park located in the Sierra Pelona Mountains in northern Los Angeles County, California. It is located in the town of Agua Dulce, between the suburbs of Santa Clarita and Palmdale. The area is also visible from the Antelope Valley Freeway.
Exploration geophysics is an applied branch of geophysics and economic geology, which uses physical methods, such as seismic, gravitational, magnetic, electrical and electromagnetic at the surface of the Earth to measure the physical properties of the subsurface, along with the anomalies in those properties. It is most often used to detect or infer the presence and position of economically useful geological deposits, such as ore minerals; fossil fuels and other hydrocarbons; geothermal reservoirs; and groundwater reservoirs.
Coronation Island is the largest of the South Orkney Islands, 25 nautical miles (46 km) long and from 3 to 8 nautical miles wide. The island extends in a general east-west direction, is mainly ice-covered and comprises numerous bays, glaciers and peaks, the highest rising to 1,265 metres (4,150 ft).
The geology of Wales is complex and varied; its study has been of considerable historical significance in the development of geology as a science. All geological periods from the Cryogenian to the Jurassic are represented at outcrops, whilst younger sedimentary rocks occur beneath the seas immediately off the Welsh coast. The effects of two mountain-building episodes have left their mark in the faulting and folding of much of the Palaeozoic rock sequence. Superficial deposits and landforms created during the present Quaternary period by water and ice are also plentiful and contribute to a remarkably diverse landscape of mountains, hills and coastal plains.
The geology of Ireland consists of the study of the rock formations on the island of Ireland. It includes rocks from every age from Proterozoic to Holocene and a large variety of different rock types is represented. The basalt columns of the Giant's Causeway together with geologically significant sections of the adjacent coast have been declared a World Heritage Site. The geological detail follows the major events in Ireland's past based on the geological timescale.
Rocks State Park is a public recreation area located in and around Deer Creek Valley near Pylesville, Harford County, Maryland. The state park's 1,060 acres (430 ha) preserve the geologic formation known as the King and Queen's Seat and other features in three non-contiguous areas near the junction of Maryland Route 24 and Maryland Route 165. It is managed by the Maryland Department of Natural Resources.
Nili Fossae is a group of large, concentric grabens on Mars, located in the Syrtis Major quadrangle. They have been eroded and partly filled in by sediments and clay-rich ejecta from a nearby giant impact crater, the Isidis basin. It is located at approximately 22°N, 75°E, and has an elevation of −0.6 km (−0.37 mi). Nili Fossae was on the list of potential landing sites of the Mars Science Laboratory, arriving in 2012, but was dropped before the final four sites were determined. Although not among the last finalists, in September 2015 it was selected as a potential landing site for the Mars 2020 rover, which will use the same design as Curiosity, but with a different payload focused on astrobiology.
Seale Chalk Pit is a 1.2-hectare (3.0-acre) geological Site of Special Scientific Interest west of Guildford in Surrey. It is a Geological Conservation Review site and part of the Seale Chalk Pit and Meadow 3-hectare (7.4-acre) private nature reserve, which is managed by the Surrey Wildlife Trust.
High Rocks is a 3.2-hectare (7.9-acre) geological Site of Special Scientific Interest west of Tunbridge Wells in East Sussex and Kent. It is a Geological Conservation Review site.
Guernsey has a geological history stretching further back into the past than most of Europe. The majority of rock exposures on the Island may be found along the coastlines, with inland exposures scarce and usually highly weathered. There is a broad geological division between the north and south of the Island. The Southern Metamorphic Complex is elevated above the geologically younger, lower lying Northern Igneous Complex. Guernsey has experienced a complex geological evolution with multiple phases of intrusion and deformation recognisable.
The Eden Rocks are two rocks lying 1.5 km off the east coast of Dundee Island, at the northern end of the Antarctic Peninsula. A small island was reported there on 30 December 1842 by Captain James Clark Ross of the Royal Navy, who named it "Eden Island" for Captain Charles Eden. Following a survey by the Falkland Islands Dependencies Survey in 1953, it was reported that the feature consists of two rocky islets rising to about 90 m in height and lying close together.
A geological period is one of the several subdivisions of geologic time enabling cross-referencing of rocks and geologic events from place to place.
