In the intro part, you have to mention briefly what Magma is and its composition.
In the main body, you have to relate magma with the rock formation, specially igneous rocks, and then discuss various roles of magma in our life in points.
The most important aspect of the answer will be economic impact like mineral formation like iron, silica etc. Other aspects in the discussion will be role of magma in crust formation which helped in agriculture and how it has helped in the survival of humans; fertile land for various crops, like cotton in the form of black soil; building material in the form of granites and pumice; basalt rock usage in concrete which is a major constituent of building since last several decades.
Magma is composed of molten rock and is stored in the Earth’s crust. Lava is magma that reaches the surface of our planet through a volcano vent. Magma can cool to form an igneous rock either on the surface of the Earth or beneath the surface of the Earth.
Without magma cooling and rock formation, farming communities would not be able to grow food, certain building materials would not be available and our atmosphere would not have its oxygen-rich environment. Various important aspects of magma in the development of our life are:
- Billions of years ago, Earth’s atmosphere was composed mainly of silicate vapor.
- During early volcanic eruptions, carbon dioxide and water vapor were among some of the gases released into Earth’s atmosphere through magma.
- The release of these gases helped Earth form its aerobic atmosphere.
- The most fertile land in the world can be found where magma have been accumulating over centuries.
- Magma are filled with minerals that, when broken down, provide plants with rich nutrients.
- Farmers plant and harvest lush crops in these areas.
- Imagine a rock that becomes so hot it melts. Many minerals start out in liquids that are hot enough to melt rocks.
- Magma cools slowly inside Earth, which gives mineral crystals time to grow large enough to be seen clearly.
- When magma erupts onto Earth’s surface, it is called lava. Lava cools much more rapidly than magma. Crystals do not have time to form and are very small.
- The chemical composition between minerals that form rapidly or slowly is often the same, only their size differs.
- The molecules may match up with different molecules to form new minerals as the rock cools.
- Therefore, Magma is source of our all economic development as it provided us with minerals.
- Once magma, or lava, reaches the surface, it cools rapidly. After it has completely cooled, magma solidifies into black rocks, which are used in soap and abrasive cleaning materials.
- Dried lava is also used to build roads and buildings.
- Perhaps the most important building materials available from magma are Granite and Marble.
- Granite and related marble industries are considered one of the oldest industries in the world; existing as far back as Ancient Egypt.
- The Hawaiian islands were created by volcanic eruptions millions of years ago.
- These underwater volcanoes erupted numerous times, causing a buildup of magma to be pushed toward the surface.
- Volcanoes occur in the Pacific Plate, which is located over an underwater hot spot and moves at 8 centimeters per year. The movement of the Pacific Plate is important in the continuous formation of islands.
- Many plateaus form as magma deep inside the Earth pushes toward the surface but fails to break through the crust. Instead, the magma lifts up the large, flat, impenetrable rock above it.
- Important plateaus like Colorado Plateau, Columbia Plateau, Deccan Plateau of India and Mascarene Plateau in the Indian Ocean (one of the few underwater features clearly visible from space) are result of magma accumulation towards the Earth’s surface.
Formation of Igneous Rocks
- Igneous rocks were THE first rocks. They formed from magma as the various celestial materials coalesced into a sphere and began to separate out into the iron core, mantle and crust.
- Those rocks of the crust were the first igneous rocks.
- As the molten material fractionated and began to form various minerals those mineral assemblages formed the first igneous rocks.
- Some over time formed assemblages of “acidic” rocks which were lighter and more buoyant than the denser heavier basaltic or basic rocks, which formed the ocean basins, whereas the acid rocks formed the more buoyant continents.
- After this, the well known rock cycle began giving birth
- Movement of the crust through tectonics gave rise to metamorphic rocks which are just altered forms of the other two due to high temperatures and pressure.
- These same tectonics gave rise to the formation of “economic” minerals such as gold, iron, silver and other commercially valuable metals and non-metallic earth materials that have commercial value.
As we can see, magma helped humans in almost all aspects of their life, be it atmosphere, landforms, agricultural land, minerals or building material. Man worked with the products of magma to create a world that we inhabit now. Without them, perhaps there would not have been an advanced human life as it exists now.