Earth Science

Earth science is the study of the Earth's structure, properties, processes, and four and a half billion years of biotic evolution. They include the geologic, hydrologic, and atmospheric sciences with the broad aim of understanding Earth's present features and past evolution and using this knowledge to benefit humankind. Earth science may also include the study of natural hazards, climate and environmental change, groundwater, lakes, oceans, earthquakes, volcanoes, tectonics, minerals, fossils, soils, rocks, sediments, and...

 MOUNTAINS

Mountains are formed when two continental plates collide, since both plates has almost the same weight and thickness neither of the plates will sink and instead they crumple and fold until the rocks are forced up, to form mountain range.


We suppose there is a subduction zone where the oceanic plate dives below the continental plate, the rest of the plate is also pulled by the slab pool, it may happen that there is both oceanic and continental crust on that plate. Due to the movement of the plate the continental crust also arrives at the subduction zone, now to continental plates collide both plates are lighter than the underlying asthenosphere as a result there is little to no subduction the plates are pushed together and they folds, sometimes you can clearly see the rock has been compressed a high mountain range is created by folding the higher the mountain range is called an neurogenic belt but not only the top of the crust is folded, the continental crust also gets much thicker at the bottom.


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The highest mountain range outside Asia 

Geological history of the Andes


Tectonic pressures and volcanic activity gave shape the earth, South America been lifted up from sea levels, started showing the mountains we climb this days.

The Nazca plate in the base of the Pacific Ocean and the Brazilian Shield crashed together and created mountain structures. A large portion of magma was also pushed upwards by the same phenomenon. All of this aroused volcanic activity along the coast. Several volcanic cones emerged and formed most of the volcanic range. Some of the volcanoes are still active and smoke from time to time.

The rocky outcrops formed the Eastern sections of the range (including Apolobamba, Cordillera Real, and Quimsa Cruz ranges in Bolivia), and the volcanic cones made up


How the Andes mountain was made

The tectonic activity in the Andean region has led to intense volcanic activity, significant uplift, and the creation of towering peaks. The Andes showcase the dynamic geological processes occurring at convergent plate boundaries, contributing to the formation of one of the longest mountain ranges in the world.


The breakup of Pangaea dispersed these plates outward, and the collision of two of these plates—the continental South American Plate and the oceanic Nazca Plate—gave rise to the mountain-building activity that produced the Andes Mountains


When did the Andes mountains form?

The Andes Mountains were formed as a result of subduction between the Nazca Plate and the South American Plate. 

The Andes were formed by tectonic activity whereby earth is uplifted as one plate (oceanic crust) subducts under another plate (continental crust).  To get such a high mountain chain in a subduction zone setting is unusual  which adds to the importance of trying to figure out when and how it happened.  However, the timing of when the Andean mountain chain uplift occurred has been a topic of some controversy over the past ten years. 

The prevailing view is that the Andes became a mountain range between ten to six million years ago when a huge volume of rock dropped off the base of the Earth’s crust in response to over-thickening of the crust in this region.  When this large portion of dense material was removed, the remaining portion of the crust underwent rapid uplift. 

Andes has a great source of minerals, 45 percent of the world's copper production, and nearly 30 percent of silver production, and significant amounts of lead, zinc, gold, as well as a variety of industrial materials and chemicals.

The type of rocks in the Andes Mountain

Here in the Andes Mountain, you can mainly find an extrusive rock that is called Andesite. Andesites are mostly found in lava flows, that’s because they are formed at subduction zones (where one tectonic plate slides between a second plate), Because of the rapid cooling of the lava rapid cooling of the lava, small crystals are formed (they are so small that a magnifying glass is required to see).

Volcanic Rocks

Andesite

Named after the Andes, this fine-grained volcanic rock is abundant in the region. It is a type of intermediate volcanic rock that often forms as a result of the subduction-related volcanic activity. Metamorphic: This type of rock is formed from pressure and heat applied to rock to form a new type of rock. In this mountain range, marble can be found in abundance and is often gathered for economic purposes.  

Basalt

Another volcanic rock commonly found in the Andes, basalt is often associated with the volcanic eruptions in the region. 

Metamorphic Rocks

Schist

The process of crustal compression and regional metamorphism in the Andes can lead to the formation of schist, a metamorphic rock with medium to coarse-grained foliated texture. 

Slate

Metamorphosed shale can give rise to slate, which is another metamorphic rock present in certain areas. 

Sedimentary Rocks

Sandstone

Sandstone is a sedimentary rock composed primarily of sand-sized mineral particles, rock fragments, and  organic matter 

Shale

Shale is a sedimentary rock that forms from the compression and consolidation of fine-grained clay and silt particles. 

Chemical bonding


Andesite (Volcanic Rock):


Chemical Bonding: Andesite comprises minerals like plagioclase feldspar, pyroxene, and amphibole. The bonding involves both ionic and covalent bonding. For instance, plagioclase feldspar exhibits ionic bonding between aluminum and oxygen, and covalent bonding within the silicon-oxygen tetrahedral structure.

Contribution to Characteristics: The combination of ionic and covalent bonding influences the overall stability and structure of andesite. The specific minerals and their bonding arrangements contribute to physical properties such as hardness, cleavage, and color.


Basalt (Volcanic Rock):


Chemical Bonding: Basalt consists of minerals like plagioclase feldspar, pyroxene, and olivine. The chemical bonding involves ionic and covalent bonding, particularly within the silicon-oxygen tetrahedral structure of the minerals.

Contribution to Characteristics: The bonding in basalt influences its physical properties, including density, hardness, and color. The presence of minerals like olivine may introduce variations in the overall composition, contributing to the distinctive characteristics of basalt.

Schist (Metamorphic Rock):


Chemical Bonding: Schist often contains minerals like mica, quartz, and feldspar. The bonding includes both ionic and covalent bonding. Micas, such as biotite and muscovite, have strong covalent bonds within their sheets.

Contribution to Characteristics: Covalent bonding within mica minerals contributes to their sheet-like structure and basal cleavage. This influences the foliated texture of schist and its ability to split along parallel planes.

Slate (Metamorphic Rock):


Chemical Bonding: Slate is derived from the metamorphism of shale and is composed of clay minerals. The bonding in clay minerals involves covalent bonds within the individual mineral layers.

Contribution to Characteristics: Covalent bonding within clay minerals contributes to the compact and fine-grained texture of slate. It influences the rock's cleavage and its ability to split into thin, flat sheets.

Sandstone (Sedimentary Rock):


Chemical Bonding: Sandstone is composed mainly of sand-sized mineral particles, cemented together. The bonding involves primarily silica cementation, with minerals like quartz being predominant.

Contribution to Characteristics: The bonding in sandstone influences its hardness, porosity, and resistance to weathering. The presence of quartz contributes to its durability and resistance to chemical weathering.

Shale (Sedimentary Rock):


Chemical Bonding: Shale is formed from the compression and consolidation of fine-grained clay and silt particles. The bonding involves covalent bonds within the clay minerals and weak van der Waals forces between layers.

Contribution to Characteristics: Covalent bonding contributes to the cohesive nature of shale, and weak van der Waals forces allow the rock to split along bedding planes. The fine-grained texture and layering are a result of these bonding characteristics.