Definition of Lithosphere (Earth’s Skin Layer) and Its Function, Facts, Thickness

Definition of Lithosphere

The word lithosphere comes from the Greek words lithos meaning rock and sphera meaning layers. The lithosphere is the outermost layer of the earth’s crust and consists of rock with an average thickness of 1200 km. The lithosphere is the uppermost layer of the earth’s crust consisting of rock, generally this layer occurs from chemical compounds that are rich in SO 2. That is why the lithosphere is often called the silicate layer. According to Klarke and Washington, the rock or lithosphere on the earth’s surface is almost 75% composed of silicon oxide and aluminum oxide.

The main constituent of the lithosphere layer is rock consisting of a mixture of similar or dissimilar minerals that are loosely or densely bonded to each other. The parent rock forming the lithosphere is magma, which is incandescent molten rock that has very high temperatures and is found under the earth’s crust. Magma will undergo several processes of change until it becomes igneous rock, sedimentary rock and metamorphic rock.

The lithosphere plays an important role in plant life. Soil is formed when the rocks on the surface of the lithosphere undergo degradation, erosion or other physical processes into small rocks to sand. Furthermore, this part is mixed with the results of the introduction of organic components of living things which then form soil that can be used as a place for living organisms.

Soil is a source of various types of minerals for living things. In their natural form, these minerals are in the form of rocks that are layered on the earth’s surface. Through the process of erosion, the minerals that are the source of food for these living creatures are often carried by rivers to the sea and deposited on the seabed.

That is why the lithosphere layer is often called the silicate layer with an average thickness of 30 km which consists of 2 parts, namely:

1. The upper lithosphere is land with about 35% or 1/3 of the way.
2. The lower lithosphere is the ocean with about 65% or 2/3 of the way.

The Earth’s lithosphere includes the crust and upper part of the Earth’s mantle which makes the outermost layer of the planet Earth hard. The lithosphere is supported by the asthenosphere which in this case is the weaker, hotter and deeper part of the mantle.

Structure of the Earth’s Skin Layer (Lithosphere)

Structure of the Earth's Skin Layer (Lithosphere)

Rocks are not just hard objects in the form of stones in everyday life, but also in the form of clay, volcanic ash, sand, gravel and so on. The thickness of the earth’s crust is uneven, the skin of the earth on the continents or on land is thicker than under the oceans.

Earth is composed of several layers, namely:

1. Barisphere is a layer of the earth’s core which is a solid material composed of nife layers (niccolum = nickel and ferum = iron) with a radius of ± 3,470 km.

2. The intermediate layer is the layer above the nife which is 1700 km thick. This layer, also known as the mantle asthenosphere, is a high-temperature, incandescent liquid material. Its density is 5 g/cm 3.

3. The lithosphere is the outermost layer located above the intermediate layer with a thickness of 1200 km with an average density of 2.8 grams/cm 3.

Types of Earth’s Skin Layer (Lithosphere)

The lithosphere, also known as the Earth’s crust, consists of two parts:

1. Damn layer

namely the layer of the earth’s crust which is composed of silicon metal and aluminum, its compounds are in the form of SiO 2 and Al 2 O 3 . In this unlucky layer (silicium and aluminum), there are sedimentary rocks, granite andesite, types of metamorphic rocks, and other rocks found on continental lands. The sial layer, also known as the crust, is solid and the rock is about 35 km apart.

The earth’s crust is divided into two parts:

1. Continental crust: is a solid body consisting of granite on the top and igneous basalt on the bottom. It is this crust that constitutes the continents.

2. Oceanic crust: is a solid object consisting of sediment in the sea at the top, then below it is a volcanic rock and the bottom is composed of gabbro and peridotite igneous rocks. This crust occupies the ocean floor.

2. Sima coating (silicon magnesium)

namely the layer of the earth’s crust which is composed of silica and magnesium metals in the form of SiO 2 and MgO compounds. This layer has a higher specific gravity than the sial layer because it contains iron and magnesium, namely ferrous magnesium minerals and basalt rock. The layer is a material that is elastic and has an average thickness of 65 km.

The boundaries between the lithosphere and asthenosphere are distinguished in terms of their response to stresses, which means that the lithosphere remains solid for relatively long geological periods and changes like a viscous liquid.

Because of that, the lithosphere was split into several tectonic plates which resulted in continental motion due to convection that occurred in the asthenosphere.

3. Lithosphere-forming rocks/materials

The lithosphere is composed of three main types of material with the basic material for its formation is magma with various different processes. The following is a rock material that makes up the lithosphere,

4. Igneous Rock ( Igneous Rock )

Igneous rocks are rocks formed from incandescent magma that solidifies, with about 80% of the rock material that composes the Earth’s crust is igneous rock. Based on the formation of frozen magma. Igneous rocks are divided into three types:

1. Deep Igneous Rocks ( Plutonic/Hibiscus)

Deep igneous rocks occur from the slow freezing of magma while it is still deep in the earth’s crust. Examples of deep igneous rocks are granite, diorite, and gabbro.

2. Gang/Korok Igneous Rock

Igneous rock occurs from magma that congeals in the passageway between the magma chamber and the earth’s surface. Magma that seeps between the layers of the lithosphere undergoes a faster freezing process, so that the mineral crystals that are formed are not all large. A mixture of mineral crystals of unequal size is a characteristic of korok igneous rocks.

3. Outer Igneous Rock

Outer igneous rock occurs from magma that comes out of the magma chamber frozen on the earth’s surface (such as magma resulting from volcanic eruptions). Examples of external igneous rocks are: basalt, diorite, andesite, obsidian, scoria, pumice ( pumice ).

5. Sedimentary Rock ( Sedimentary Rock )

Sedimentary rocks are mineral rocks that have formed on the surface of the earth that have undergone weathering. The parts that are released from the weathering are released and transported by water, wind, or by glaciers which are then deposited or sedimented and a diagenesis process occurs which causes these deposits to harden and become sedimentary aids. Sedimentary rocks based on the formation process consists of:

1. Clastic Sedimentary Rock
2. Chemical Sedimentary Rock

6. Organic Sedimentary Rock

Based on the energy that transports it, sedimentary rock consists of:

1. Aeris or Aeolis. Sedimentary Rocks
2. Glacial Sedimentary Rock
3. Aquatic Sedimentary Rock
4. Marine Sedimentary Rock
5. Malihan Rock ( Metamorphic )

Malian rocks are formed due to the addition of temperature or the addition of high pressure and occur simultaneously in sedimentary rocks.

Plate Tectonics and Their Forms

The theory of Plate Tectonics ( Plate Tectonics ) is a theory in the field of geology that was developed to provide an explanation for the evidence of large-scale movements carried out by the Earth’s lithosphere. This theory has included and also replaced the Continental Displacement Theory which was first proposed in the first half of the 20th century and the concept of seafloor spreading which was developed in the 1960s.

The outermost part of the Earth’s interior is made up of two layers. At the top is the lithosphere, which consists of the crust and the top of the Earth’s mantle, which is rigid and dense. Beneath the lithosphere is the asthenosphere which is solid but can flow like a liquid very slowly and over very long geological timescales because of its low viscosity and shear strength. Deeper still, the part of the mantle below the asthenosphere becomes even more rigid. The cause is not colder temperatures, but high pressure.

The lithosphere is divided into tectonic plates. On earth, there are seven major plates and many smaller plates. These lithospheric plates are superimposed on the asthenosphere. They move relative to one another at plate boundaries, either divergent (away), convergent (collision), or transform (sideways). Earthquakes, volcanic activity, mountain formation, and ocean trench formation all commonly occur in areas along plate boundaries. The lateral movement of the plates is usually 50-100 mm/a.

Plate Movement (Plate Movement)

Based on the direction of movement, the boundaries between tectonic plates are divided into 3 types, namely divergent, convergent, and transform. In addition, there is another type that is quite complex but rare, namely a triple junction where three crustal plates meet.

1. Divergent Limit

Occurs when two tectonic plates move apart ( break apart ). When a tectonic plate breaks apart, the lithosphere thins and splits, forming divergent boundaries. On the oceanic plate, this process causes seafloor spreading. While on the continental plate, this process causes the formation of a rift valley due to the gap between the two plates that are moving away from each other.

The Mid -Atlantic Ridge is one of the best-known examples of divergence, stretching from north to south along the Atlantic Ocean, separating Europe and Africa from the Americas.

2. Convergent Limit

Occurs when two tectonic plates are pushed towards the earth’s crust causing them to move against each other. Areas where an oceanic plate is pushed under a continental plate or another oceanic plate are called subduction zones. In this zone earthquakes often occur. Volcanic ridges and oceanic trenches are also formed in this region.

There are 3 kinds of convergent limits, namely:

1) Converging Continental – Oceanic ( Oceanic – Continental ) Plates

When an oceanic plate sinks under a continental plate, it enters the higher-temperature asthenosphere, where it melts. In the lithosphere layer directly above it, a row of volcanoes is formed ( volcanic mountain range ). While on the seabed right where the subduction occurs, an oceanic trench is formed.

The Andes Mountains in South America are one of the mountains formed by this process. This mountain range was formed from the convergence of the Nazka Plate and the South American Plate.

2) Convergence of the Oceanic-Oceanic Plate ( Oceanic-Oceanic )

One oceanic plate subducts under another oceanic plate, causing a trench on the seabed, and a series of volcanoes parallel to that trench, also on the seabed. The peaks of some of these volcanoes rise to the surface, forming a group of volcanic islands ( volcanic island chain ).

The Aleutian Islands in Alaska are one example of a volcanic island from this process. The island was formed from the convergence of the Pacific Plate and the North American Plate.

3) Converging Continental Plates ( Continental – Continental )

One continental plate is subducting under another continental plate. Since both are continental plates, the material is neither too dense nor heavy enough to sink into the asthenosphere and melt. The area on the impact side hardens and thickens, forming a mountain range.

The Himalayas and the Tibetan Plateau are examples of mountains formed by this process. This mountain range is formed from the convergence of the Indian Plate and the Eurasian Plate.

Transform Limit

Occurs when two tectonic plates move against each other, i.e. move parallel but in opposite directions. The two do not support each other or support each other. The transform boundaries are generally on the seabed, but some are on land, one of which is the San Andreas Fault in California, USA. This fault is a meeting between the North American Plate which is moving to the southeast and the Pacific plate which is moving northwest.

The Benefits of the Lithosphere for Life

The lithosphere is the part of the earth that directly affects life and has enormous benefits for life on earth. The upper lithosphere is a habitat for humans, animals and plants. Humans carry out activities above the lithosphere. Furthermore, the lower lithosphere contains mineral materials that are very useful for humans. Mineral or mining materials originating from the lower lithosphere include oil and gas, gold, coal, iron, nickel and tin.

As explained above, the lithosphere is the uppermost layer of the earth’s crust. Therefore, the lithosphere is a layer that can be inhabited by humans. In the lithosphere, humans live and develop. Carry out all activities in life. The lithosphere layer also provides the materials needed by humans to meet their needs. In this layer, humans can build shelter, cultivate crops, make agricultural land, plantations, etc.

The Influence of Earth’s Shapes on Life

Different forms of the earth’s surface will have an impact on human life. The various forms of the earth’s surface include beaches, lowlands, highlands, and mountains.

1. Beach

The beach is a landscape that is still affected by the state of the sea. Since childhood, coastal residents have known the sea, so they often play in the sea and are familiar with ocean waves. This causes people who live near the sea to use the sea as a source of life. So there are residents who work as fishermen, milkfish farmers, pearl seekers, seaweed keepers, etc.

2. Lowland

According to Jungian, the lowland area is located between 0-700m above sea level. This area is the center of various activities such as transportation, trade, companies, and industry. This is because transportation and communication are cheaper and smoother in lowland areas. Types of crops that are suitable to be planted in this area are coconut, rice, sugar cane and corn.

3. Plateau

The plateau region is situated at an altitude of about 700m. It is suitable for coffee and rubber plants. The agricultural system that is often used is a dryland farming system (horticulture) such as vegetables, fruits and ornamental plants.

4. Mountain area

In undeveloped areas, conditions in mountainous areas make transportation and communication very difficult. This causes population development in mountainous areas to tend to be static. Usually, the population settlements are centered in the valleys near the water source.

Leave a Comment