QUIZ – 2020: INSIGHTS STATIC , 7 December 2020 – Geography

Solution: a)

Magma is extremely hot liquid and semi-liquid rock located under Earth’s surface. Earth has a layered structure that consists of the inner core, outer core, mantle, and crust. Much of the planet’s mantle consists of magma. This magma can push through holes or cracks in the crust, causing a volcanic eruption. When magma flows or erupts onto Earth’s surface, it is called lava.

Like solid rock, magma is a mixture of minerals. It also contains small amounts of dissolved gases such as water vapor, carbon dioxide, and sulfur. The high temperatures and pressure under Earth’s crust keep magma in its fluid state.

Source

Solution: b)

Earth has 4 layers:

• The outer crust that we live on
• The plastic-like mantle
• The liquid outer core
• The solid inner core

The crust is by far the thinnest of the layers of earth. The thickness varies depending on where you are on earth, with oceanic crust being 5-10 km and continental mountain ranges being up to 30-45 km thick. Thin oceanic crust is denser than the thicker continental crust and therefore ‘floats’ lower in the mantle as compared to continental crust.

Solution: c)

The most abundant elements in the Earth’s crust include (listed here by weight percent) oxygen, silicon, aluminum, iron, and calcium.

All three rock types (igneous, sedimentary, and metamorphic) can be found in Earth’s crust.

The oldest rocks on our planet are part of the continental crust and date back approximately 4 billion years in age. Ocean crust is constantly recycled through our planet’s system of plate tectonics and only dates back to approximately 200 million years ago.

Solution: c)

Direct Sources: The most easily available solid earth material is surface rock or the rocks we get from mining areas. Besides mining, scientists have taken up a number of projects to penetrate deeper depths to explore the conditions in the crustal portions. Many deep drilling projects have provided large volume of information through the analysis of materials collected at different depths. Volcanic eruption forms another source of obtaining direct information.

Indirect Sources: Another source of information are the meteors that at times reach the earth. The other indirect sources include gravitation, magnetic field, and seismic activity.

Solution: a)

The portion of the interior beyond the crust is called the mantle. It has a density higher than the crust’s (3.4 g/cm3).

The outer core of Earth is in liquid state while the inner core is in solid state. The core is made up of very heavy material mostly constituted by nickel and iron. It is sometimes referred to as the nife layer.