Category: Geography Notes PPT

Saltmarsh, also known as saltwater marsh, coastal salt marsh, or tidal marsh is an area of low, flat, poorly drained ground subjected to regular or occasional flooding by saltwater or brackish water and is covered by salt-tolerant plants such as grasses, herbs, or low shrubs. Saltmarsh plays an important role in the aquatic food web and provides nutrients to the coastal waters. Salt marsh also reinforces terrestrial animals and arrange coastal protection. 

Salt Marsh Evolution

Saltmarsh or coastal marsh evolve from young marshes to old marshes. In the eastern USA, the natural young marshes are vegetated for the major part with low marsh cordgrass known as Spartina alterniflora. Nutrients are carried by tidal currents through tidal channels. This enabled grasses to grow thick and lavish, so weakening the effect of tidal currents and waves accelerated the deposition rate of mud.

Erosion is minimized by the root and rhizomes of the plant. During that time, the marsh surface builds up above the high water level, high marsh species captured, defeated, and substitute the low marsh. The most stressed tolerant plant species occupy the lower reaches of the marshes while the competitive influencer occupies the upper elevation that is less stressful.  While the size of low marsh and high marsh is about equal, the ecosystem reaches the mature stage of development. 

The ongoing deposition of mud transforms the low marsh into the high marsh. Minimum water flows through the tidal channel of these elevated “ old marshes”. Accumulation of sand and mud on the high marshes metamorphose into dry land that is detached from the ocean effects. Lateral channel migration and wave attack at the bottom of the marsh cliffs are the main instruments for the erosion of mature salt marshes and their succeeding rejuvenation cycle. 

Salt Marsh Development Requirements

• Saltmarsh requires coarse-grained sediments.

• There may be no tidal currents or strong waves.

• They need salty conditions to grow. 

• They need a temperate or cool temperature. Incidental frozen temperatures do not destroy the plants.

• They demand a wide tidal range. This is crucial because it limits erosion, makes deposition of sediments possible, and causes a transparent zonation. 

Where Does Salt Marsh Found?

Saltmarsh is generally found along the bank of lagoons, shallow sea cut from the open sea, or along the bank of estuaries where rivers join the sea. In these areas, plants can easily take roots in the mud as water is calm. Saltmarsh is home to various coastal wildlife.

Salt Marsh Grass

Saltmarsh grass or cordgrass makes up the vast majority of plants in the salt marsh ecosystem and is invaluable to humans. Smooth cordgrass forms a great swaddle of vegetation that preserves tidal, coastal muds and protects the coastline from erosion. Saltmarsh cordgrass is widely used to produce salt meadow hay. The other species in these groups form smaller colonies within the salt marsh ecosystem generally in the area covering up the marsh which receives lesser saltwater flooding. 

Saltmarsh grasses or cord-grass are found abundantly along both Atlantic back bays and shores of Delaware bays. Some species are rarely found at inland sites, especially along roadsides where salt is used in winters or on areas where evaporation exceeds precipitation, creating a high water content in the soil. 

Did You Know?

• The salt marsh trail is a part of the deserted Musquodoboit railroad that has been transformed into a part of the TransCanada rail. The trail offers relaxed adventures to similar hikers and bikers.

• The salt marsh trail of Cole Harbour, Nova Scotia is a renowned walk constructed  within the Halifax regional community. This salt marsh trail offers delightful views of the salt marsh as the visitors walk along former railway turner walking tracks that cross through Cole Harbour.

• The grasses, sedges, and rushes that describe salt marsh are halophytic. It means that they are specially modified to survive in a saline habitat. 

• One acre of salt marsh can approximately absorb 1.5 millions gallon of floodwater which is equivalent to more than 2.25 Olympic size swimming pools.

• The US has approximately 3.8 million acres of salt marshes. Three-quarters of them are in the Southeast, including vast interconnected 1 million acres stretched from North California to Florida.

• Saltmarsh protects the shoreline from excessive erosion caused by wind, water, and ice. 

• Saltmarsh helps in maintaining water quality by filtering runoff and excessive nutrients.

• As per NOAA, salt marsh absorbs floodwaters and wave energy during the storm, which minimizes property damage in adjacent communities by up to 20%.

Sedimentology is a scientific discipline concerned with the physical and chemical properties of sedimentary rocks as well as the processes involved in their formation, such as sediment transportation, deposition, and lithification (conversion to rock). The interpretation of ancient environmental conditions in sediment source areas and depositional sites is a key objective of much sedimentological study. Sedimentologists examine the constituents, textures, structures, and fossil content of deposits formed in various geographic environments. They can distinguish between continental, littoral, and marine deposits in the geologic record.

Basic Principles of Sedimentological Research

• The purpose of sedimentological research is to extract information on the depositional conditions that worked to deposit the rock unit, as well as the relationship of the individual rock units in a basin, into a coherent understanding of the evolution of the sedimentary sequences and basins, and thus the Earth’s geological history as a whole. The scientific basis for this is the concept of uniformitarianism, which claims that sediments within ancient sedimentary rocks were deposited in the same way that sediments at the Earth’s surface are being deposited today.

• Sedimentological conditions are documented within the sediments as they are laid down; the current form of the sediments represents past events, and all events affecting the sediments, from the source of the sedimentary material to the stresses enacted upon them after diagnosis, are studyable.

• Recognizing younging indicators or graded bedding is crucial to understanding the sedimentary section and also the deformation and metamorphic structure of the area in older metamorphic terrains or fold and thrust belts where sediments are often deeply folded or deformed, and in older metamorphic terrains or fold and thrust belts where sediments are often intensely folded or deformed.

• Folding in sediments is studied using the initial horizontality theory, which states that sediments are deposited at their angle of repose, which is basically horizontal for most forms of sediment. When the younging path is determined, the rocks can be “unfolded” and interpreted using the sedimentary details found within them.

• The theory of lateral continuity states that, unless obstructed by a physical object or topography, sediment layers initially extend laterally in all directions.

• According to the concept of cross-cutting relationships, whatever cuts through or intrudes into the strata layers is younger than the strata layers.

Methodology

In Sedimentological Research, Sedimentologists use a variety of techniques to collect data and information about the composition and depositional conditions of sedimentary rocks, including:

• Measuring and defining the rock unit’s outcrop and distribution.

• A systematic method of recording thickness, lithology, outcrop, distribution, and contact relationships to other formations is used to describe the rock formation.

• The distribution of the rock unit, or units, is being mapped.

• Rock core descriptions (drilled and extracted from wells during hydrocarbon exploration).

• Stratigraphy of sequences.

• The progression of rock units within a basin is defined.

• The lithology of the rock is defined.

• Texture, grain size, grain form (sphericity, rounding, etc. ), sorting, and sediment composition are all measured in petrology and petrography.

• Analyzing the rock’s geochemistry.

• Radiometric dating and isotope geochemistry are used to assess the age of the rock and its affinity to source areas.

Sedimentary Rock

Sedimentary rocks are formed by the deposition or accumulation of mineral or organic particles at the Earth’s surface, followed by cementation. The processes that allow these particles to settle in place are referred to as sedimentation. Sediment is the term for the particles that make up a sedimentary rock. It may be made up of geological detritus (minerals) or biological detritus (organic matter). Weathering and erosion of existing rocks, as well as the solidification of molten lava blobs, erupted by volcanoes, created the geological detritus. Water, wind, ice, and mass movement, known as agents of denudation, carry geological detritus to the deposition site. Biological detritus is made up of the bodies and parts (mostly shells) of dead aquatic species, as well as their faeces, suspended in water and gradually accumulating on the water’s surface (marine snow). Sedimentation can also happen when dissolved minerals in water solution precipitate.

The sedimentary rock cover of the Earth’s crust’s continents is vast (73 percent of the current land surface), but the sedimentary rock is estimated to make up just 8% of the crust’s thickness. Sedimentary rocks form a thin layer on top of a crust that is mostly made up of igneous and metamorphic rocks. Sedimentary rocks are deposited in strata, or layers, to create a structure known as bedding. Sedimentary rocks are mostly found in sedimentary basins, which are vast structures.

Clastic sedimentary rocks, biochemical (biogenic) sedimentary rocks, chemical sedimentary rocks, and “other” sedimentary rocks produced by collisions, volcanism, and other minor processes are classified into four categories based on the processes responsible for their formation.

Sedimentary Rock Types

Clastics, carbonates, evaporites, and chemicals are the four main groups of sedimentary rocks.

• Clastic rocks are made up mainly of fragmental material and are formed by the weathering and erosion of precursor rocks. The predominant grain size and composition of clastic rocks are used to classify them. The word “Clastic Sedimentary Rocks” was once used to describe silica-rich clastic sedimentary rocks, but clastic carbonate rocks have also been found. The word siliciclastic sedimentary rocks are more accurate.

• Organic sedimentary rocks, which form coal and oil shale deposits and are usually located within basins of clastic sedimentary rocks, are significant deposits produced from the deposition of biological detritus.

• Carbonates are made up of a number of carbonate minerals that have been precipitated by organic and inorganic processes. The majority of carbonate rocks are usually made up of reef material.

• Evaporites are created when water evaporates at the Earth’s surface, and the most common evaporites are halite and gypsum.

• Precipitation of minerals from aqueous solution forms chemical sedimentary rocks, which have some carbonates. Jaspilite and chert are two examples.

Importance of Sedimentary Rocks

Sedimentary rocks provide a wide range of products that are used by both modern and ancient societies.

• Since it is a metamorphosed limestone, marble is an example of sedimentary rocks being used in the pursuit of aesthetics and sculpture.

• Uses in architecture: Dimension stone and architectural stone derived from sedimentary rocks are used, most notably slate, a meta-shale, for roofing and sandstone for load-bearing buttresses.

• Clay for pottery and ceramics, including bricks; cement and lime extracted from limestone are examples of ceramics and industrial materials.

• They have significant deposits of SEDEX ore deposits of lead-zinc-silver, copper, gold, tungsten, Uranium, and a variety of other precious minerals, gemstones, and industrial minerals, including heavy mineral sands ore deposits.

• Petroleum geology is based on the ability of sedimentary rocks to produce petroleum oil deposits. Sedimentary rocks include coal and oil shale. Sedimentary successions contain a considerable portion of the world’s uranium energy resources.

• Sedimentary rocks are home to a significant portion of the world’s freshwater aquifers. Our knowledge of the rocks that contain these aquifers is vital to our understanding of their extent and the amount of water that can be drained from them (the reservoir).

Why Sedimentology Matters?

The majority of the Earth is covered in sediments and sedimentary rocks, and the rest is weathered. The reshaping of the Earth’s crust has had a tremendous impact on the world, impacting everything from life evolution to mountain range tectonics. The events and processes that formed the surface of Earth – and other rocky planets – are recorded in sediments and sedimentary rocks. They provide a temporal structure for connecting processes on the inside of the Earth to those on the surface. They are important for:

1. History of our planet: Sedimentary rocks have characteristics that help us understand ancient depositional conditions, such as the evolution of organisms and the environments they lived in, how climate has changed over time, where and when faults were involved, and so on.

2. Economic Resources: Most oil and gas migrates through sedimentary rocks, and most reservoirs are hosted in sedimentary rocks. Petroleum reservoirs have organic-rich, sedimentary source rocks that contain petroleum when heated. Sedimentary rocks are the most common source of water aquifers. Due to water-rock interactions, the composition of the rocks has a significant impact on water quality. Economic minerals such as gold and diamonds are eroded from other rocks and concentrated in particular areas during sediment transport in sedimentary rocks.

3. Geology of the Environment: Sediments occupy two-thirds of the continents and almost the entire ocean floor, accounting for 89 percent of the Earth’s surface. They are the hosts of the biosphere, as well as the majority of the rocks with which we interact directly or indirectly. Sedimentation and degradation are greatly influenced by our behaviour as humans. Understanding our effect on the climate, as well as the environment’s impact on us, necessitates a thorough understanding of sediments and their transport.

Sedimentary Petrology

Sedimentary petrology is concerned with the description and classification of sedimentary rocks, the interpretation of the transportation and deposition processes of the sedimentary materials forming the rocks, the environment that existed at the time the sediments were deposited, and the alteration (compaction, cementation, and chemical and mineralogical modification) of the sediments.

Sedimentary petrology is divided into two divisions. Carbonate rocks, such as limestones and dolomites, are composed primarily of calcium carbonate (calcite) and calcium magnesium carbonate (dolomite). The other major branch of sedimentary petrology is concerned with non-calcareous sediments and sedimentary rocks. Sandstones, claystones, siltstones, conglomerates, glacial till, and various sandstones, siltstones, and conglomerates are among them (e.g., the graywacke-type sandstones and siltstones).

Conclusion

Sedimentology is a scientific discipline concerned with the physical and chemical properties of sedimentary rocks as well as the processes involved in their formation, such as sediment transportation, deposition, and lithification (conversion to rock). The interpretation of ancient environmental conditions in sediment source areas and depositional sites is a key objective of much sedimentological study. Sedimentologists examine the constituents, textures, structures, and fossil content of sedimentary deposits. 

They can distinguish between continental, littoral, and marine deposits in the geologic record. The current form of the sediments represents past events, and all events affecting the sedimentary material are studyable. Sedimentologists use a variety of techniques to collect data and information about the composition and depositional conditions of sedimentaries. The theory of lateral continuity states that unless obstructed by a physical object or topography, sediment layers initially extend laterally in all directions.

Soil horizon can be defined as the parallel layer of the soil surface. Each layer has its own composition of physical, chemical and biological characteristics, they quite differ from each of the layers above and beneath each layer. Horizons have definite physical features such as the colour and texture of each layer of the soil. These soil horizons are described both in absolute terms like in terms of the particle size distribution for texture, and in terms, they are relatively ‘coarser’ or ‘sandier’ than all the soil horizons above and below.

In our prevailing section, we will plunge deeper into the Soil Horizon Definition in detail, know about each layer of soil and its benefits. 

Horizons of Soil

In this section, we will continue to explain the soil horizons layers. 

As studied vividly on the subject ‘the types of the soil’, we know there are varied types of soil, with each one having distinct characteristics. If anyone would dig down deep into any of the soils, one can see the soil is made of layers, or the horizons (O, A, E, B, C, R). Putting the horizons together, they will structure into a soil profile. Each of the profiles informs about the nature of the particular soil which has been dug deep. Majorly these soils have three major horizons that are – A, B, C and some have an organic horizon as well denoted by O. The horizons are:

1. O Horizon Which Contains Hummus or any Organic Matter: 

This layer is mostly filled with organic content like the decomposing leaves. The O horizon is particularly thinner in most soils, while thicker in others, also the horizon may not be present at all in other types of soil.

2. A Which is the Topsoil: 

Minerals are present in this layer which are generated from the parent material with the organic matter that is being incorporated. This layer serves as a good material for the plants and other organisms to live.

3. E is Known as the Eluviated Layer: 

Here clay, minerals, and other organic matter, with a concentration of sand and silt particles of quartz are present. They are mainly found in older soils and forest soils.

4. B the Subsoil Layer:

They are quite rich in minerals, the mineral seeps down from the A or E horizons and gets accumulated in this layer.

5. C the Parent Material: 

The deposit is present at the Earth’s surface, this is the place from which actually the soil is originated. 

6. R, the Bedrock Layer: 

This layer has a mass of rock like granite, basalt, quartzite, limestone and even sandstone, this layer forms the parent material for some soil.

Thus, clearly, the Soil Horizons are explained. In the next section, we will take up each of the layers in the soil profile and determine the quality of the soil that influenced such a layer. 

Soil Profile Horizons 

The Different Layers of Soil have different functions to do. While the soil profile is quite defined as the vertical section of the soil which forms the ground surface, this seeps downwards to where the soil meets the underlying bedrocks.

The soil is arranged in layers or in horizons. They are arranged during their formation. The layers or the horizons are basically known as the soil profile. The vertical section of the soil which is exposed by a soil pit is called the soil horizon profile. The layers of soil are easily identified by their colour and texture. In presence, there are soil particles as well. The different layers of soil are as follows:

• The Topsoil

• The middle is the Subsoil

• Then, comes the Parent rock

Each of the soil layers has its respective characteristics.

Layers of Soil

The soil profile consists of the series of the horizon of soil which is layered on to one another. The horizons are represented by the letters O, A, E, C, B and R, also refer to the diagram displayed above.

The O-Horizon

The uppermost layer of the topsoil is composed of organic materials like dried leaves, grasses, and other decomposed organic matter. This layer of soil is blackish brown or dark brown in colour, the colour is for the content of organic material.  

The A-Horizon is also known as the Topsoil

This layer is also rich in organic material and commonly known as the humus layer. This majorly consists of both organic matter and other decomposed type materials. The topsoil is very soft and is thus porous in nature to hold enough air and water.

The E-Horizon

This layer has nutrients seeped down from the O and A horizons. This layer is very common in forested areas which have low clayey content.

The B-Horizon or Subsoil

This horizon is present just below the topsoil, while above the bedrock. This is comparatively much harder and more compact than the topsoil. This contains less humus, soluble minerals, and organic matter. Rather this is a site of deposition of certain minerals and metal salts like iron oxide.

The C-Horizon, Known as the Saprolite

This layer has an absence of any organic matter and is made up of broken bedrock. 

The R-Horizon

They are the compacted and cemented layer with different types of rocks like granite, basalt and limestone.

The atmosphere can be defined as the gas and the aerosol envelope which extends from the ocean land, and from the ice-covered surface of a planet to space above. The atmosphere density goes on to decrease outward, this happens because of the gravitational attraction of the earth, which pulls the gases and aerosols inward. 

In this context, we will learn about different layers of the atmosphere viz. Stratosphere, Mesosphere, Troposphere, Thermosphere. 

Stratosphere and Mesosphere

The stratosphere is typically a layer of the earth’s atmosphere. Moving upward, this will be the second layer of the atmosphere. The bottom of the stratosphere is round about 10 km above the ground situated at the middle latitudes. The top portion of the stratosphere occurs at an altitude of about 50 km. While the height of the bottom of the stratosphere keeps varying with altitude and seasons. The lower boundary of the stratosphere is known as tropopause while the upper boundary is called the stratopause.

The mesosphere is another layer of the Earth’s atmosphere. The mesosphere is right above the stratosphere and below the thermosphere layer. This layer extends from about 50 to 85 km above our planet’s earth.

The temperature gradually decreases with the height in the mesosphere. The coldest temperatures in Earth’s atmosphere are found near the region of the top of this layer. At the bottom of the mesosphere is the stratopause lies the boundary between the mesosphere and the stratosphere. 

The mesosphere is quite difficult to study, so lesser-known facts are available about this layer of the atmosphere than other layers. Weather balloons or other aircraft fail to fly high enough to reach this layer, the mesosphere. Satellites orbit above this layer cannot directly measure their traits. 

Troposphere

The troposphere is the lowermost layer of the Earth’s atmosphere and this layer is the site of all the weather occurrences on Earth. The tropopause is the boundary on the top of this layer, this separates the troposphere from the stratosphere.

75 percent of the atmosphere’s mass comes under this layer. On average, the weight of the molecules present in the air is around 14.7 lb and this covers most of the atmosphere’s water vapor. The most dominating gases are nitrogen which is 78 percent and oxygen that is 21 percent, with the remaining 1% as argon and traces of hydrogen ozone (that is formed of oxygen), with other constituents. 

Thermosphere

The thermosphere is a layer of the atmosphere that is directly related to the mesosphere and down below the exosphere. This extends from about 90 km (that is 56 miles) to between 500 and 1,000 km (which is 311 to 621 miles) above our planet.

Temperatures rise sharply in the lower thermosphere which is below 200 to 300 km altitude, then level off and hold fairly steady with the increasing altitude above that height. Here the solar activity gets strongly influenced by temperature in the thermosphere. The thermosphere is typical of about 200° C which is hotter in the daytime than at night, and this is roughly 500° C hotter at the time when the Sun is very active than at other times. 

Distance of Stratosphere, Ionosphere, Troposphere, and Mesosphere

Troposphere

The troposphere starts right at the Earth’s surface which extends 8 to 14.5 kilometers higher (which is 5 to 9 miles). The troposphere is the densest layer of the atmosphere. All-weather types are in this region.

Stratosphere

The stratosphere here starts just above the troposphere which extends up to 50 kilometers that is 31 miles high. This ozone layer functions by absorbing and scattering the solar ultraviolet radiation is in this layer.

Mesosphere

The mesosphere starts immediately above the stratosphere and this extends to 85 kilometers (which is 53 miles) high. Meteors in the space burn up in this layer.

Thermosphere

The thermosphere here starts right above the mesosphere and this extends to 600 kilometers (that is 372 miles) high. The Aurora and satellites occur in this definite layer.

The temperate zone is the area of the earth that lies between the middle latitudes, which is 40 degrees to 60 degrees to the north-south of the Equator. The temperate zones are located in the regions of the Earth between the tropic regions and the polar regions. The climate that occurs in this region is called the temperate climate. If the average yearly temperatures of these regions are calculated, they are not extreme, not burning hot nor are they freezing cold. Temperate temperature is moderate. While in the tropics, the temperatures may drastically change between the summer and winter. 

The temperate zone has the following features:

• Few parts of the temperate zone have a Mediterranean climate, that is they have a dry summer – like in Rome, Cape Town, Santiago or Adelaide.

• The northern part of the temperate zones experiences the continental climate and has severe winters like in Moscow or Minnesota; this kind of climate is called HemiBoreal climate.   

• Some places in the temperate zone experience hot summers and cold winters, like Chicago, Beijing, Budapest, or Almaty. 

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An Overview of the Temperate Climate

The temperate climate is also sometimes known as the Tepid climate. These zones, the tropic and polar zones, generally have a temperature which are of wider ranges. Also, the seasonal changes in these zones are also distinct in comparison to the tropical climates, where such variations are found to be little. Usually, the region of the earth that falls in the temperate climate zones, experiences the hot summers and the cold winters, evidence of it can be found in the cities such as Chicago, Beijing, Budapest etc. While, other parts of the temperate climate zones feel dry summers, such as Rome, Cape Town, and Santiago.

In temperate climates, along with the influence of the latitudinal positions on the change of temperature, the sea currents, the wind direction which is prevailing at the time, the largeness of the landmass, and also the altitudes, impact the temperate climates.

According to the Koppen climate classification, which is a system of climate classification that is used widely worldwide, the temperature is above -3 degrees Celsius or 26.6 degrees Fahrenheit, and below 18 degrees Celsius or 64.4 degrees Fahrenheit, is defined as the temperate climate.

The area between the Tropic of Cancer, which is approximately 23.5 degrees north latitude, and the arctic circle which is approximately 66.5 degrees north latitude, come under the north temperate zone. The Tropic of Capricorn, which is approximately 23.5 degrees south latitude, and the Antarctic circle, which is approximately 66.5 degrees south latitude- these two regions cover the south temperate zone.

Many of the climate classifications divide the temperate zone into several smaller climate zones, and this division is based on the monthly temperatures, the coldest month, and the rainfall. The humid subtropical climate, the climate of the Mediterranean, oceanic climate, and continental climate.

The Temperate climates have relatively moderate and mean annual temperatures, with average monthly temperatures which are more than 10°C in its warmest months and more than −3°C in the colder months. 

Most of the regions coming under the temperate climate present four seasons, while the temperatures can change majorly between the summer and winter. Most of the people live in temperate zones and there the human population in the coastal regions is about three times higher than the global average.

Temperature Zones of Earth

The temperate zone of the earth is divided into five distinct zones. The distinction is based on their climatic conditions, which are known as geographical zones. These zones are the North Frigid Zone, the North Temperate Zone, the Tropics, the South Frigid Zone, and the South Temperate Zone.

Warm Temperate Climate

The warm temperate climates are defined in the Koppen climate, which is classified as having the coldest month with an average temperature that drops below 18°C but which is more than −3°C. Thus, in a warm temperate climate, there is a distinct summer and winter season. The warm temperate climates will have a lot of rainfall which may be seasonal or permanent.

  

North Temperate Zone 

The North Temperate Zone, which is situated between the Arctic Circle at the 66° 33′ N and the Tropic of Cancer at 23° 27′ N, covers 25.99% of Earth’s surface. The Torrid Zone, between the Tropic of Cancer at 23° 27′ N and the Tropic of Capricorn at 23° 27′ S, covers approximately 39.78% of Earth’s surface.

Tropical and Temperate Region 

The tropical zone has a temperature of 65 degrees F or above. The tropical region is also referred to as tropical or the torrid zone. While, in the temperate region, there is a variation in temperature which is not extreme of cold nor of hot. This region lies between the equator and the pole. 

The tropical regions are the area of the Earth which is between the Tropic of Cancer and the Tropic of Capricorn, from the latitude lines 23.5 degrees north and south of the equator, respectively. While the temperate regions are between the subtropical and the polar regions.

Temperate Zone Latitude

The two temperate zones of the earth  it consist of tepid latitudes. Here the sun is never at the top of the head, here the climate is mild which is generally ranging from warmer to cooler regions. The four annual seasons which occur in these areas are – Spring, Summer, Autumn, Winter. Europe, Northern Asia, and Central America come under the North Temperate zone. While South America and South Australia come under the Southern Temperate Zone.

Conclusion

Therefore, we can summarize that the temperate climate has average temperature between 0 and 20°C, and it rarely experiences extreme temperature and precipitation. The vegetation of temperate regions include deciduous forests, warm temperate forests, and savannah. The temperate climate zone covers most of the regions of North America, all of Europe, most part of northern Asia, and the southern parts of South America and Australia.

A drainage pattern can be well briefed concerning the topological features from where a stream gets runoff through its flow and the groundwater flow. These flows can be well divided by the watersheds (topological barriers). A watershed is the combined stream tributaries that flow to someplace along the channel of the stream. There are various types of drainage patterns across the world, but in this article, we will focus more on the Trellis Drainage pattern and its various details. The article provided by ‘s team mainly talks about trellis drainage pattern, trellis geology, examples of trellis drainage pattern, formation and flow in a draw restrain is pattern diagram and actuality, difference between various types of drainage patterns such as rectangle a drainage pattern, trellis drainage pattern, dendritic drainage pattern.

Trellis Drainage Pattern

Also known as the Trellis drainage system or the Trellis River pattern is the one that we can mostly find across the southern regions of a map. Experts define the trellis drainage pattern as the indication of structural control by varying types of eroded and folded sedimentary rocks. Across a humid region, resistant rocks like sandstone from the ridges and the non-resistant ones like shale and limestone form the valleys. Sometimes, there is the occurrence of a dip angle, causing the asymmetric ridges.

Trellis Geology

A Trellis pattern of the river has the same geometry as the standard garden trellis; along a strike valley, smaller tributaries are fed into from the steeper slopes across the mountain’s sides. These tributaries then enter into the main river perpendicularly, leading to a trellis-like appearance of the system. Trellis drainage definition states that they form where the hard and soft formations exist on both sides of any river. The formations must also be reflective of height and accentuated by erosion. Trellis drainage pattern is the folded mountains’ characteristic, like that of the Appalachian Mountains in Northern America and Northern Trinidad.

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Example of Trellis Drainage Pattern

The streams near the Southeast of Piney Mountain and Little Allegheny Mountain are known to form a trellis stream pattern. Here, the resistant bedrock ridges get drained by the shorter stream, and the non-resistant units form valleys with the subsequent streams. As is expected from a general Trellis drainage pattern definition, the stream locations before exposure of this surface imprint upon the current Pattern. This imprint is then evident in how the streams cut through the ridges.

Formation and Flow in a Trellis Drainage Pattern Diagram and Actuality

By the time the erosion wears away the surface and exposes the folded sedimentary rocks below, the streams stay there. They further continue eroding down, and there they encounter the resistant beds; the streams continue eroding them too. This leads to the formation of newer slopes and streams on the slopes, and these then become the tributaries for the mainstream in the area. The principal streams are superimposed on the current landscape. These landforms where the streams cut through ridges are called the water gaps, and they form with the running water and Fluvial Processes. Streams then continue flowing from higher elevation to lower, down the slope. The stream extends its headwaters and forms tributaries near the source; this process is called Headward Erosion. 

Difference Between Trellis and Rectangular Drainage Pattern 

Rectangular Drainage Pattern: It is the drainage pattern where the main streams and their tributaries display numerous right-angle bends and exhibit sections of approximately the same length. It indicates the streams that follow prominent faults or the joint systems that break the rocks into rectangular blocks. Various forms of weathering on the joint systems or faults in any bedrock localize the streamflow, leading to the production of a Rectangular pattern. These drainage patterns are developed mainly on firmly joined rocky terrains.

Trellis Drainage System: This type of drainage system occurs when the sub-parallel streams erode a valley across the less resistant formations and sides. These beds are mainly visualized as steeply dipping and might also be a part of a folding system. These tributaries also intersect at right angles where the water gap cuts through some more complex formations. A river joined by the tributaries at approximately right angles develops a Trellis drainage pattern. It is mainly found where the hard and soft rocks exist parallel to one another.

Difference Between Dendritic and Trellis Drainage Pattern

The dendritic drainage pattern develops at the regions where the river channels follow the terrain’s slope. Here the mainstream and its tributaries resemble the branches of a tree. In contrast, a Trellis river pattern is formed when a river and its tributaries join at approximately 90-degrees and are found where hard and soft rocks exist parallel to each other.

Trellis drainage pattern is a type of drainage pattern that is taught very briefly in class 11 geography, in chapter 3 called drainage system. This chapter is taught in schools that follow the curriculum set by the Central board of secondary education. The study notes provided by on the types of drainage patterns can be studied by class 11 students who are pursuing geography, however, these notes are also useful for UPSC aspirants as geography holds a substantial weightage in the exam held by the UPSC. IAS/IFS aspirants Who want to get a quick revision of the basic concepts covered in geography can refer to these notes provided by . As they are written in an extremely simplified language they can help you get ahead of the exam preparation phase.

The study material provided on ‘s website on the topic of trellis drainage patterns is extremely beneficial as it contains minute details that might be missed by students preparing for an examination. This article mainly covers information on the trial of drainage patterns however there are various drainage patterns that can be studied on ‘s website. The study material acts as a reference guide and is extremely precise and detailed. ‘s research team includes many expert geography teachers who are well-versed in the field and therefore they have produced the study notes through extensive research and through the critical analysis of previous year question papers.