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Why are the major hot deserts in the Northern Hemisphere primarily situated along the western coasts of continents?
The Sahara, Arabian, and Sonoran deserts, among other large hot deserts of the Northern Hemisphere, are positioned strategically along the western shores of continents. This geographic pattern is the outcome of particular meteorological and geographical variables rather than a coincidence. InfluenceRead more
The Sahara, Arabian, and Sonoran deserts, among other large hot deserts of the Northern Hemisphere, are positioned strategically along the western shores of continents. This geographic pattern is the outcome of particular meteorological and geographical variables rather than a coincidence.
Influence of Cold Ocean Currents: The existence of cold ocean currents along these western shores is one of the main causes. The air above them is cooled by cold currents such as the California and Canary currents. This colder air warms up and loses relative humidity as it passes over the land, creating dry, arid conditions that help deserts grow.
High Pressure Systems: The horse latitudes, or subtropical high-pressure belts, are important. Dry air descends from these high-pressure zones, which are located about 30 degrees north and south of the equator. This air warms as it falls, preventing precipitation and the formation of clouds. This produces the dry conditions found in deserts.
Rain Shadow Effect: Due to the rain shadow effect, mountain ranges close to the western shore might promote the formation of deserts. Cooling as it climbs the windward side of mountains, moist air from the ocean releases moisture as rain. Inland desert conditions result from the dry air that descends on the leeward side.
Continentality: The western regions of continents benefit from their distance from large bodies of water, which results in lower levels of precipitation and moisture. This “continentality” adds to the dry weather that characterizes deserts.
Combining Factors: Along the western coasts of continents in the Northern Hemisphere, deserts flourish due to a combination of factors including high pressure systems, rain shadow effects, cold currents, and continentality.
See lessGiving a brief account of the lakes formed due to Earth's movement, discuss the economic and ecological significance of lakes.
Lakes are defined as large areas of water bodies that occupy the hollows of the Earth's surface, are surrounded by land, and are not connected to the seas except by rivers or streams. Lakes can be formed due to various factors such as Earth's movement, glaciation, volcanic activity, erosion, depositRead more
Lakes are defined as large areas of water bodies that occupy the hollows of the Earth’s surface, are surrounded by land, and are not connected to the seas except by rivers or streams. Lakes can be formed due to various factors such as Earth’s movement, glaciation, volcanic activity, erosion, deposition, and human and biological activities.
The lakes formed due to Earth’s movements are as follows:
Human life is closely linked to the water bodies, and lakes are no different. They not only play a crucial role in the economic, social, and cultural life of people but are also a key link in our ecological system. Economic significance of lakes
Ecological significance of lakes:
Lakes all over the world are facing threats due to climatic and anthropogenic factors. A plan to protect lakes encompassing local bodies, local population, and national and state level agencies focusing on the conservation and rejuvenation of lakes is the need of the hour.
See lessExplaining their formation, provide an account of the various kinds of deserts found across the world along with their characteristics.
A desert is an extremely dry area of land with extreme environments and sparse vegetation. They are likely to develop in areas where annual precipitation is less than 250 mm. It is one of Earth's major types of ecosystems, supporting a community of distinctive flora and fauna specially adapted to thRead more
A desert is an extremely dry area of land with extreme environments and sparse vegetation. They are likely to develop in areas where annual precipitation is less than 250 mm. It is one of Earth’s major types of ecosystems, supporting a community of distinctive flora and fauna specially adapted to the harsh environment.
Geologists group deserts into five categories:
Deserts are found on every continent and cover about one-fifth of Earth’s land area. They are home to around 1 billion people-one-sixth of the Earth’s population. It has been observed that in semi-arid areas that border deserts, climate change and human activities have led to increased desertification.
See lessDiscuss the supporting evidence as well as the counter arguments against Alfred Wegener's theory of continental drift.
It was in 1912 that the idea of continental drift gained a strong come-back, when Alfred Wegener propose for it; who supposed that landmasses were consolidated together all at once into big continent wholly called Pangaea and had since then driven separately. There are several solid grounds supportiRead more
It was in 1912 that the idea of continental drift gained a strong come-back, when Alfred Wegener propose for it; who supposed that landmasses were consolidated together all at once into big continent wholly called Pangaea and had since then driven separately. There are several solid grounds supporting this theory:
Grounds in Favor:
Among which are the Fit of Continents, meaning that if you ignore all other lines on your map and simply draw a line between their coastlines (the continental shelf), South America appears to fit perfectly in with Africa.
Fossil EvidenceSimilar fossil species were found on different continents which is an indication that these land masses once upon a time existed in close physical proximity, like the Mesosaurus.
The Geological Evidence: Rock formations or mountain ranges (like the Appalachian-Caledonian belt) that are similar between continents, indicating they share a common history Geologic feature -> Isostasy in Madagascar and Seychelles
Paleoclimate Evidence: The geological record contains rocks of glacial origin that are now distributed in essentially isolated localities across a number of continents, suggesting the existence at some time in the past of climates much more like those seen today than implied by barnacles.
Objections:
Mechanistic Explanation : A major criticism of Wegener’s theory was that there seemed to be no plausible mechanism by which continents could plow their way through the solid rock covering Earth nearly three miles deep.
Lack of Geological Processes: Some geologists claimed that the forces he suggested required to prod continents into motion were poorly understood (which was true) and Wegener’s theory lacked specific geological phenomena to explain how continental drift actually takes place.
Timing and Rate: Some of the issues raised by critics centered on the time and speed of continental drift as elucidated by Wegener where they noted that the movement of the continents was very fast and had not had a set time-frame.
Thus, one can state that Alfred Wegner offered a new magnificent theory of the continental drift which was based on the existence of geological, fossil and climatic evidence about the continental movement. Despite of its advantages like the match between continents and the related geological history, there were several objections concerning the absence of the reasonable mechanism and the detailed geological processes of the continental drift. These debates have since been followed by other debates that have facilitated new types of works and the coming up with of the theory of plate tectonics that explain the movement of Earth’s continent and oceanic plates.
See lessAnalyze how plateaus impact both regional and global climate patterns.
Alteration of circulation patterns, precipitation patterns and temperatures, plateaus, which are flattened landforms raised notably higher than the surrounding land, have a substantive impact on climate on local, regional and even global contexts. At the regional scale, Plateaus are massive barriersRead more
Alteration of circulation patterns, precipitation patterns and temperatures, plateaus, which are flattened landforms raised notably higher than the surrounding land, have a substantive impact on climate on local, regional and even global contexts.
At the regional scale, Plateaus are massive barriers to the atmospheric flow disrupting weather greatly. For example, the tectonically formed Tibetan Plateau is the highest and the largest plateau in the world which significantly influences the Asian monsoon systems. It uplifts the tropical moist air from the Indian Ocean and makes it rise, cool and condense making the southern side have heavy rainfall and the northern side to be arid and referred to as the ‘rain shadow’ regions. This dynamic affects the regions’ water systems, distribution of agricultural land, and ecosystems.
Moreover, plateaus help in regulation of temperature at certain regions. It is a well-known fact that any higher ground will always be relatively colder as the altitude increases. One example is Deccan Plateau in India that have comparatively moderate climate to the lowlands and thus support diverse flora and fauna along with the different types of agriculture. Such temperature disparities can therefore trigger the formation of microclimates that has an impact on both the biological diversity as well as the numerous undertakings.
On a global level, there are key circulation systems that are affected by plateaus. The surface of the Tibetan Plateau gets warm in summer causing a formation of a high pressure system that can change the route of the jet stream hence modifying the weather in the Northern Hemisphere. Such changes may include shifts in storm routes, changes in precipitation areas, and other effects which are experienced as far as North America and Europe, which proves that plateaus significantly affect global climate.
Besides, it has been established that plateaus have an active function in the cycling of carbon on a global level. Alpine plateaus have specialized vegetation coming up due to the harsh environmental conditions and they sequester large amounts of carbon. But the human activities like deforestation and mining help in the emission of stored carbon into the atmosphere thus contributing to the global warming.
To sum up, plateaus bear a major impact on the regional and global climate as they determine circulation, precipitation, temperature regulation, and carbon storage. It is crucial to identify these impacts then as the information will help forecast and perhaps lessen the effects of climate change.
See lessHow does the theory of plate tectonics help in explaining the differences in the formation of the Himalayas and Andes mountains?
The Plate tectonics is a theory that explains the movement of the Earth's lithospheric plates and consequent formation of major landforms like mountains and events like volcanoes and earthquakes. The theory states that the Earth's lithosphere, which is the outermost layer of the planet, is broken inRead more
The Plate tectonics is a theory that explains the movement of the Earth’s lithospheric plates and consequent formation of major landforms like mountains and events like volcanoes and earthquakes. The theory states that the Earth’s lithosphere, which is the outermost layer of the planet, is broken into several large plates that move relative to each other.
The lithospheric plates rest on the underlying asthenosphere. These plates move due to the convection currents in the mantle, which are driven by the Earth’s internal heat sources, such as the radioactive decay of elements.
Formation of Himalayan Mountains:
Formation of Andes Mountains:
Therefore, there is a fundamental difference in the formation of Himalayas and Andes. While Himalayas are formed due to collision of two continental plates, the Andes are formed by the convergence of oceanic plate and continental plate (subduction of one plate under another). This subduction leads to formation of volcanoes in Andes such as Ojos Del Salado, Cotopaxi, Chimborazo etc., which are absent in the case of Himalayas.
See lessGive a brief account of various erosional and depositional landforms created by the movement of glaciers.
Answer: Masses of ice moving as sheets over the land or as linear flows down the slopes of mountains in broad trough-like valleys are called glaciers. They are formed through the processes of accumulation, compaction, and recrystallization of snow. The movement of a glacier is very slow and it movesRead more
Answer: Masses of ice moving as sheets over the land or as linear flows down the slopes of mountains in broad trough-like valleys are called glaciers. They are formed through the processes of accumulation, compaction, and recrystallization of snow. The movement of a glacier is very slow and it moves from a few centimeters to a few meters in a day. During this movement, a glacier forms various landforms. Erosional landforms created by the movement of a glacier are the following:
- Till deposits: The unassorted coarse and fine debris dropped by the melting glaciers is called glacial till. Most of the rock fragments in the till are angular to subangular in form.
- Outwash plains: Streams form by melting ice at the bottom, sides, or lower ends of glaciers. Some amount of rock debris small enough to be carried by such melt-water streams is washed down and deposited. Such glaciofluvial deposits are called outwash plains.
- Moraines: They are long ridges of deposits of glacial till. Based on their orientation with the glacier, they are termed terminal moraines, lateral moraines, horse-shoe-shaped ridge, ground moraines, and medial moraines.
- Eskers: These are sinuous ridges formed as a result of the melting of ice. During summers, the water accumulates beneath the glacier and flows like streams in a channel beneath the ice. This causes very coarse materials like boulders and blocks along with some minor fractions of rock debris carried into these streams and settle in the valley of ice beneath the glacier giving rise to eskers.
- Drumlins: Drumlins are smooth oval-shaped ridge-like features composed mainly of glacial till with some masses of gravel and sand.
See lessExplain the concept of diastrophism and the processes involved.
Answer: Diastrophism is an endogenic process and consists of all processes that move, elevate, or build up portions of the earth's crust. It is the process that brings about changes in the configuration of the surface of the earth. They move, elevate, or build up portions of the earth's crust owingRead more
Answer: Diastrophism is an endogenic process and consists of all processes that move, elevate, or build up portions of the earth’s crust. It is the process that brings about changes in the configuration of the surface of the earth. They move, elevate, or build up portions of the earth’s crust owing to the energy emanating from within the earth. This energy is mostly generated by radioactivity, rotational and tidal friction, and primordial heat from the origin of the earth. The process of diastrophic movements is of the following types:
Through the processes of orogeny, epeirogeny, earthquakes, and plate tectonics, there can be faulting and fracturing of the crust. All these processes cause pressure, volume, and temperature (PVT) changes which in turn induce the metamorphism of rocks.
See lessDifferentiate between endogenic and exogenic geomorphic processes. Also, highlight the significance of weathering.
Answer: The endogenic and exogenic forces causing physical stresses and chemical actions on earth materials and bringing about changes in the configuration of the surface of the earth are known as geomorphic processes. While, diastrophism and volcanism are endogenic geomorphic processes, weathering,Read more
Answer: The endogenic and exogenic forces causing physical stresses and chemical actions on earth materials and bringing about changes in the configuration of the surface of the earth are known as geomorphic processes. While, diastrophism and volcanism are endogenic geomorphic processes, weathering, mass wasting, erosion and deposition are exogenic geomorphic processes. The differences between the two processes are as follows:
Significance of Weathering: Weathering is the action of elements of weather and climate over the earth’s materials. There are a number of processes within weathering that act either individually or together to affect the earth’s materials in order to reduce them to a fragmental state.
- Weathering processes are responsible for breaking down the rocks into smaller fragments and preparing the way for the formation of not only regolith and soils but also erosion and mass movements.
- Weathering is an important process in the formation of soils. Biodiversity depends upon vegetation, which in turn, is dependent upon the depth of weathering mantles.
- Weathering aids mass wasting, erosion, and reduction of relief. Also, changes in landforms are a consequence of erosion.
- Weathering of rocks and deposits helps in the enrichment and concentrations of certain valuable ores of iron, manganese, aluminum, copper, etc., which are of great importance to the national economy.
- Weathering processes are conditioned by many complex geological, climatic, topographic and vegetative factors.
See lessWhat is continental drift theory? Discuss the evidence that supports it.
Answer: Continental drift is the movement of the Earth's continents relative to each other. The hypothesis that continents 'drift' was fully developed by Alfred Wegener in 1912. However, it was not until the development of the theory of plate tectonics in the 1960s, that a sufficient geological explRead more
Answer: Continental drift is the movement of the Earth’s continents relative to each other. The hypothesis that continents ‘drift’ was fully developed by Alfred Wegener in 1912. However, it was not until the development of the theory of plate tectonics in the 1960s, that a sufficient geological explanation of that movement was understood. According to Wegener, all the continents formed a single continental mass named Pangaea, which was surrounded by a mega-ocean Panthalassa. He argued that, around 200 million years ago, the supercontinent, Pangaea, began to split and the drift started. Pangaea first broke into two large continental masses Laurasia and Gondwanaland forming the northern and southern components respectively. Subsequently, Laurasia and Gondwanaland continued to break into various smaller continents that exist today. Wegener suggested that the movement responsible for the drifting of the continents was caused by pole-fleeing force and tidal force. Following evidence in support of the continental drift theory was given by him:
Wegener’s theory was criticized on the grounds of forces such as pole-fleeing force and tidal force, which are considered to be too weak to be able to move continents. Plate tectonics accommodated continental motion through the mechanism of seafloor spreading. There is now considerable evidence that the continents are parts of lithospheric plates and these plates move over the asthenosphere and cause continents to drift. New rock is created by volcanism at mid-ocean ridges and returned to the Earth’s mantle at ocean trenches..
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