Highlands or uplands are any mountainous region or elevated mountainous plateau. Speaking, upland refers to ranges of hills up to 500–600 m. Highland is reserved for ranges of low mountains; the best known highlands in the anglosphere are the Scottish Highlands in northern Scotland, the mountainous region north and west of the Highland Boundary Fault. The Highland council area is a local government area in the Scottish Highlands and Britain's largest local government area. Many countries have areas that are or unofficially referred to as highlands. Other than Scotland, these include parts of Tibet, Canada, Eritrea, Ghana, Papua New Guinea and Cantabria. Synonymous terms used in other countries include high country, used in New Zealand, New South Wales, Victoria and Southern Queensland in Australia, parts of the United States, used in South Africa and Roof of the World, used for Tibet; the highlands in Australia are above the elevation of 500 metres. These areas receive snowfalls through winter.
Most of the highlands lead up to large alpine or sub-alpine mountainous regions such as the Australian Alps, Snowy Mountains, Great Dividing Range, Northern Tablelands and Blue Mountains. The most mountainous region of Tasmania is the Central Highlands area, which covers most of the central western parts of the state. Many of these areas are elevated alpine regions. A spine of mountains runs the length of the island of New Guinea, forming a populous highlands region; the Central Highlands of Sri Lanka these are rain forests, where the elevation reaches 2,500 metres above sea level. The Sri Lanka montane rain forests represent the montane and submontane moist forests above 1,000 metres in the central highlands and in the Knuckles mountain range. Half of Sri Lanka's endemic flowering plants and 51 percent of the endemic vertebrates are restricted to this ecoregion; the highlands of Iceland cover about 40% of the country and are inhospitable to humans. They are considered to be any land above 500 meters.
Additionally, the mountainous natural region of the Thai highlands is found in Northern Thailand. The Cameron Highlands are a highland hill station in Northern Malaysia. Shillong in India in the state of Meghalaya is a hill station, surrounded by highlands. Officers of the British Raj referred to Shillong as "The Scotland of the East". Highland continents – or terrae – are areas of topographically unstable terrain, with high peaks and valleys, they resemble highlands on Earth. They can be found on Venus, Mercury and the Moon. Planum Highlander
Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, the processes by which they change over time. Geology can include the study of the solid features of any terrestrial planet or natural satellite such as Mars or the Moon. Modern geology overlaps all other earth sciences, including hydrology and the atmospheric sciences, so is treated as one major aspect of integrated earth system science and planetary science. Geology describes the structure of the Earth on and beneath its surface, the processes that have shaped that structure, it provides tools to determine the relative and absolute ages of rocks found in a given location, to describe the histories of those rocks. By combining these tools, geologists are able to chronicle the geological history of the Earth as a whole, to demonstrate the age of the Earth. Geology provides the primary evidence for plate tectonics, the evolutionary history of life, the Earth's past climates. Geologists use a wide variety of methods to understand the Earth's structure and evolution, including field work, rock description, geophysical techniques, chemical analysis, physical experiments, numerical modelling.
In practical terms, geology is important for mineral and hydrocarbon exploration and exploitation, evaluating water resources, understanding of natural hazards, the remediation of environmental problems, providing insights into past climate change. Geology is a major academic discipline, it plays an important role in geotechnical engineering; the majority of geological data comes from research on solid Earth materials. These fall into one of two categories: rock and unlithified material; the majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth. There are three major types of rock: igneous and metamorphic; the rock cycle illustrates the relationships among them. When a rock solidifies or crystallizes from melt, it is an igneous rock; this rock can be weathered and eroded redeposited and lithified into a sedimentary rock. It can be turned into a metamorphic rock by heat and pressure that change its mineral content, resulting in a characteristic fabric.
All three types may melt again, when this happens, new magma is formed, from which an igneous rock may once more solidify. To study all three types of rock, geologists evaluate the minerals; each mineral has distinct physical properties, there are many tests to determine each of them. The specimens can be tested for: Luster: Measurement of the amount of light reflected from the surface. Luster is broken into nonmetallic. Color: Minerals are grouped by their color. Diagnostic but impurities can change a mineral’s color. Streak: Performed by scratching the sample on a porcelain plate; the color of the streak can help name the mineral. Hardness: The resistance of a mineral to scratch. Breakage pattern: A mineral can either show fracture or cleavage, the former being breakage of uneven surfaces and the latter a breakage along spaced parallel planes. Specific gravity: the weight of a specific volume of a mineral. Effervescence: Involves dripping hydrochloric acid on the mineral to test for fizzing. Magnetism: Involves using a magnet to test for magnetism.
Taste: Minerals can have a distinctive taste, like halite. Smell: Minerals can have a distinctive odor. For example, sulfur smells like rotten eggs. Geologists study unlithified materials, which come from more recent deposits; these materials are superficial deposits. This study is known as Quaternary geology, after the Quaternary period of geologic history. However, unlithified material does not only include sediments. Magmas and lavas are the original unlithified source of all igneous rocks; the active flow of molten rock is studied in volcanology, igneous petrology aims to determine the history of igneous rocks from their final crystallization to their original molten source. In the 1960s, it was discovered that the Earth's lithosphere, which includes the crust and rigid uppermost portion of the upper mantle, is separated into tectonic plates that move across the plastically deforming, upper mantle, called the asthenosphere; this theory is supported by several types of observations, including seafloor spreading and the global distribution of mountain terrain and seismicity.
There is an intimate coupling between the movement of the plates on the surface and the convection of the mantle. Thus, oceanic plates and the adjoining mantle convection currents always move in the same direction – because the oceanic lithosphere is the rigid upper thermal boundary layer of the convecting mantle; this coupling between rigid plates moving on the surface of the Earth and the convecting mantle is called plate tectonics. The development of plate tectonics has provided a physical basis for many observations of the solid Earth. Long linear regions of geologic features are explained as plate boundaries. For example: Mid-ocean ridges, high regions on the seafloor where hydrothermal vents and volcanoes exist, are seen as divergent boundaries, where two plates move apart. Arcs of volcanoes and earthquakes are theorized as convergent boundaries, where one plate subducts, or moves, under another. Transform boundaries, such as the San Andreas Fault system, resulted in widespread powerful earthquakes.
Plate tectonics has provided a mechan
Montane ecosystems refers to any ecosystem found in mountains. These ecosystems are affected by climate, which gets colder as elevation increases, they are stratified according to elevation. Dense forests are common at moderate elevations. However, as the elevation increases, the climate becomes harsher, the plant community transitions to grasslands or tundra; as elevation increases, the climate becomes cooler, due to a decrease in atmospheric pressure and the adiabatic cooling of airmasses. The change in climate by moving up 100 meters on a mountain is equivalent to moving 80 kilometers towards the nearest pole; the characteristic flora and fauna in the mountains tend to depend on elevation, because of the change in climate. This dependency causes life zones to form: bands of similar ecosystems at similar altitude. One of the typical life zones on mountains is the montane forest: at moderate elevations, the rainfall and temperate climate encourages dense forests to grow. Holdridge defines the climate of montane forest as having a biotemperature of between 6 and 12 °C, where biotemperature is the mean temperature considering temperatures below 0 °C to be 0 °C.
Above the elevation of the montane forest, the trees thin out in the subalpine zone, become twisted krummholz, fail to grow. Therefore, montane forests contain trees with twisted trunks; this phenomenon is observed due to the increase in the wind strength with the elevation. The elevation where trees fail to grow is called the tree line; the biotemperature of the subalpine zone is between 3 and 6 °C. Above the tree line the ecosystem is called the alpine zone or alpine tundra, dominated by grasses and low-growing shrubs; the biotemperature of the alpine zone is between 1.5 and 3 °C. Many different plant species live in the alpine environment, including perennial grasses, forbs, cushion plants and lichens. Alpine plants must adapt to the harsh conditions of the alpine environment, which include low temperatures, ultraviolet radiation, a short growing season. Alpine plants display adaptations such as rosette structures, waxy surfaces, hairy leaves; because of the common characteristics of these zones, the World Wildlife Fund groups a set of related ecoregions into the "montane grassland and shrubland" biome.
Climates with biotemperatures below 1.5 °C tend to consist purely of ice. Montane forests occur between the subalpine zone; the elevation at which one habitat changes to another varies across the globe by latitude. The upper limit of montane forests, the forest line or timberline, is marked by a change to hardier species that occur in less dense stands. For example, in the Sierra Nevada of California, the montane forest has dense stands of lodgepole pine and red fir, while the Sierra Nevada subalpine zone contains sparse stands of whitebark pine; the lower bound of the montane zone may be a "lower timberline" that separates the montane forest from drier steppe or desert region. Montane forests differ from lowland forests in the same area; the climate of montane forests is colder than lowland climate at the same latitude, so the montane forests have species typical of higher-latitude lowland forests. Humans can disturb montane forests through agriculture. On isolated mountains, montane forests surrounded by treeless dry regions are typical "sky island" ecosystems.
Montane forests in temperate climate are one of temperate coniferous forest or temperate broadleaf and mixed forest, forest types that are well known from northern Europe, northern United States, southern Canada. The trees are, however not identical to those found further north: geology and climate causes different related species to occur in montane forests. Montane forests around the world tend to be more species-rich than those in Europe, because major mountain chains in Europe are oriented east-west. Montane forests in temperate climate occur in Europe, in North America, south-western South America, New Zealand and Himalaya. Montane forests in Mediterranean climate are warm and dry except in winter, when they are wet and mild; these forests are mixed conifer and broadleaf forests, with only a few conifer species. Pine and Juniper are typical trees found in Mediterranean montane forests; the broadleaf trees show more variety and are evergreen, e.g. evergreen Oak. This type of forest is found in the Mediterranean Basin, North Africa and the southwestern US, Iran and Afghanistan.
In the tropics, montane forests can consist of broadleaf forest in addition to coniferous forest. One example of a tropical montane forest is a cloud forest, which gains its moisture from clouds and fog. Cloud forests exhibit an abundance of mosses covering the ground and vegetation, in which case they are referred to as mossy forests. Mossy forests develop on the saddles of mountains, where moisture introduced by settling clouds is more retained. Depending on latitude, the lower limit of montane rainforests on large mountains is between 1,500 and 2,500 metres while the upper limit is from 2,400 to 3,300 metres; the subalpine zone is the biotic zone below the tree line around the world. In tropical regions of Southeast Asia the tree line may be above 4,000 m, whereas in Scotland it may be as low as 450 m. Species that occur in this zone depend on the location of the zone on the Earth, for example, snow gum in Australia, or subalpine larch, mountain h
In ecology, a habitat is the type of natural environment in which a particular species of organism lives. It is characterized by both biological features. A species' habitat is those places where it can find food, shelter and mates for reproduction; the physical factors are for example soil, range of temperature, light intensity as well as biotic factors such as the availability of food and the presence or absence of predators. Every organism has certain habitat needs for the conditions in which it will thrive, but some are tolerant of wide variations while others are specific in their requirements. A habitat is not a geographical area, it can be the interior of a stem, a rotten log, a rock or a clump of moss, for a parasitic organism it is the body of its host, part of the host's body such as the digestive tract, or a single cell within the host's body. Habitat types include polar, temperate and tropical; the terrestrial vegetation type may be forest, grassland, semi-arid or desert. Fresh water habitats include marshes, rivers and ponds, marine habitats include salt marshes, the coast, the intertidal zone, reefs, the open sea, the sea bed, deep water and submarine vents.
Habitats change over time. This may be due to a violent event such as the eruption of a volcano, an earthquake, a tsunami, a wildfire or a change in oceanic currents. Other changes come as a direct result of human activities; the introduction of alien species can have a devastating effect on native wildlife, through increased predation, through competition for resources or through the introduction of pests and diseases to which the native species have no immunity. The word "habitat" has been in use since about 1755 and derives from the Latin habitāre, to inhabit, from habēre, to have or to hold. Habitat can be defined as the natural environment of an organism, the type of place in which it is natural for it to live and grow, it is similar in meaning to a biotope. The chief environmental factors affecting the distribution of living organisms are temperature, climate, soil type and light intensity, the presence or absence of all the requirements that the organism needs to sustain it. Speaking, animal communities are reliant on specific types of plant communities.
Some plants and animals are generalists, their habitat requirements are met in a wide range of locations. The small white butterfly for example is found on all the continents of the world apart from Antarctica, its larvae feed on a wide range of Brassicas and various other plant species, it thrives in any open location with diverse plant associations. The large blue butterfly is much more specific in its requirements. Disturbance is important in the creation of biodiverse habitats. In the absence of disturbance, a climax vegetation cover develops that prevents the establishment of other species. Wildflower meadows are sometimes created by conservationists but most of the flowering plants used are either annuals or biennials and disappear after a few years in the absence of patches of bare ground on which their seedlings can grow. Lightning strikes and toppled trees in tropical forests allow species richness to be maintained as pioneering species move in to fill the gaps created. Coastal habitats can become dominated by kelp until the seabed is disturbed by a storm and the algae swept away, or shifting sediment exposes new areas for colonisation.
Another cause of disturbance is when an area may be overwhelmed by an invasive introduced species, not kept under control by natural enemies in its new habitat. Terrestrial habitat types include forests, grasslands and deserts. Within these broad biomes are more specific habitats with varying climate types, temperature regimes, soils and vegetation types. Many of these habitats grade into each other and each one has its own typical communities of plants and animals. A habitat may suit a particular species well, but its presence or absence at any particular location depends to some extent on chance, on its dispersal abilities and its efficiency as a coloniser. Freshwater habitats include rivers, lakes, ponds and bogs. Although some organisms are found across most of these habitats, the majority have more specific requirements; the water velocity, its temperature and oxygen saturation are important factors, but in river systems, there are fast and slow sections, pools and backwaters which provide a range of habitats.
Aquatic plants can be floating, semi-submerged, submerged or grow in permanently or temporarily saturated soils besides bodies of water. Marginal plants provide important habitat for both invertebrates and vertebrates, submerged plants provide oxygenation of the water, absorb nutrients and play a part in the reduction of pollution. Marine habitats include brackish water, bays, the open sea, the intertidal zone, the sea bed and deep / shallow water zones. Further variations include rock pools, sand banks, brackish lagoons and pebbly beaches, seagrass beds, all supporting their own flora and fauna; the benth
In geology, a high island or volcanic island is an island of volcanic origin. The term can be used to distinguish such islands from low islands, which are formed from sedimentation or the uplifting of coral reefs. There are a number of "high islands" which rise no more than a few feet above sea level classified as "islets or rocks", while some "low islands", such as Makatea, Niue and Banaba, as uplifted coral islands, rise several hundred feet above sea level; the two types of islands are found in proximity to each other among the islands of the South Pacific Ocean, where low islands are found on the fringing reefs that surround most high islands. Volcanic islands arise above a so-called hotspot; the differences in geology and topography between high and low islands mean a lot in terms of habitability for humans: high islands above a certain size have fresh groundwater, while low islands do not. This hampers human settlement on many low islands. Archipelagic apron – A fan-shaped sloping region of sea floor found around oceanic islands Atoll – Ring-shaped coral reef formed over a subsiding oceanic volcano, with a central lagoon and islands around the rim Galápagos Islands Krakatoa Archipelago Low island Volcanic arc – A chain of volcanoes formed above a subducting plate Micronesian culture: High island and low island cultures at Britannica.com.
Plate tectonics 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 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, the rigid outermost shell of a planet, is broken into tectonic plates; the Earth's lithosphere is composed of many minor plates. Where the plates meet, their relative motion determines the type of boundary: convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, oceanic trench formation occur along these plate boundaries; the relative movement of the plates ranges from zero to 100 mm annually. Tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust.
Along convergent boundaries, subduction, or one plate moving under another, carries the lower one down into the mantle. In this way, the total surface of the lithosphere remains the same; this prediction of plate tectonics is referred to as the conveyor belt principle. Earlier theories, since disproven, proposed gradual expansion of the globe. Tectonic plates are able to move because the Earth's lithosphere has greater mechanical strength than the underlying asthenosphere. Lateral density variations in the mantle result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from spreading ridges due to variations in topography and density changes in the crust. At subduction zones the cold, dense crust is "pulled" or sinks down into the mantle over the downward convecting limb of a mantle cell. Another explanation lies in the different forces generated by tidal forces of the Moon; the relative importance of each of these factors and their relationship to each other is unclear, still the subject of much debate.
The outer layers of the Earth are divided into the asthenosphere. The division is based on differences in mechanical properties and in the method for the transfer of heat; the lithosphere is more rigid, while the asthenosphere is hotter and flows more easily. In terms of heat transfer, the lithosphere loses heat by conduction, whereas the asthenosphere transfers heat by convection and has a nearly adiabatic temperature gradient; this division should not be confused with the chemical subdivision of these same layers into the mantle and the crust: a given piece of mantle may be part of the lithosphere or the asthenosphere at different times depending on its temperature and pressure. The key principle of plate tectonics is that the lithosphere exists as separate and distinct tectonic plates, which ride on the fluid-like asthenosphere. Plate motions range up to a typical 10–40 mm/year, to about 160 mm/year; the driving mechanism behind this movement is described below. Tectonic lithosphere plates consist of lithospheric mantle overlain by one or two types of crustal material: oceanic crust and continental crust.
Average oceanic lithosphere is 100 km thick. Because it is formed at mid-ocean ridges and spreads outwards, its thickness is therefore a function of its distance from the mid-ocean ridge where it was formed. For a typical distance that oceanic lithosphere must travel before being subducted, the thickness varies from about 6 km thick at mid-ocean ridges to greater than 100 km at subduction zones. Continental lithosphere is about 200 km thick, though this varies between basins, mountain ranges, stable cratonic interiors of continents; the location where two plates meet is called a plate boundary. Plate boundaries are associated with geological events such as earthquakes and the creation of topographic features such as mountains, mid-ocean ridges, oceanic trenches; the majority of the world's active volcanoes occur along plate boundaries, with the Pacific Plate's Ring of Fire being the most active and known today. These boundaries are discussed in further detail below; some volcanoes occur in the interiors of plates, these have been variously attributed to internal plate deformation and to mantle plumes.
As explained above, tectonic plates may include continental crust or oceanic crust, most plates contain both. For example, the African Plate includes the continent and parts of the floor of the Atlantic and Indian Oceans; the distinction between oceanic crust and continental crust is based on their modes of formation. Oceanic crust is fo
Slide Mountain Ocean
The Slide Mountain Ocean was an ancient ocean that existed between the Intermontane Islands and North America beginning around 245 million years ago in the Triassic period. It is named after the Slide Mountain Terrane, composed of rocks from the ancient oceanic floor. There was a subduction zone on the Slide Mountain Ocean's floor called the Intermontane Trench where the Intermontane Plate was being subducted under North America; the floor of the Slide Mountain Ocean was pushed up onto the ancient margin of North America