Test:Inside Our Earth - 1

Thinnest layer of the earth is Crust. It is about 35 km km on continental masses & 5 km on ocean floors. Mantle extends upto 2900 km. Core is innermost layer with radius of 3500 km and is made up nicke (ni) & iron(fe).

The main mineral constituents of the continental mass are silica and alumina. It is thus called sial (si-silica and al-alumina). The oceanic crust mainly consists of silica and magnesium; it is therefore called sima (si-silica and ma-magnesium).

There are three main types of rock: igneous rock, metamorphic rock, and sedimentary rock.

Igneous rocks form from molten rock, and rarely have fossils in them.

Metamorphic rocks have been put under great pressure, heated, squashed or stretched, and fossils do not usually survive these extreme conditions.

Generally it is only sedimentary rocks that contain fossils.

The innermost layer of the earth is known as the core. It is divided into inner core and outer core. It comprises of a high concentration of nickel and iron. It is believed to be the source of the earths magnetism.

Sandstone is a very common rock. It is made of sand grains cemented together. The grains were once part of a beach or a desert. 

Unlike the mineral-rich crust and mantle, the core is made almost entirely of metal—specifically, iron and nickel. The shorthand used for the core’s iron-nickel alloys is simply the elements’ chemical symbols—NiFe. 

The Earth’s structure can be defined in several ways, but general, we see the Earth as having a solid crust on the outside, an inner and an outer core, and the mantle in between.

The Earth's outer core has a radius of about 3,500 km. The inner core is more than 5,000 °C hot but in solid state due to the high pressure. The outer core is liquid and somewhat cooler.

Fossils are mainly found where animals and plants were buried by silt being deposited on top of them, So they are more common in the sea than on land.

Ferrous" means generally "containing iron". The word is derived from the Latin word ferrum ("iron"). Ferrous metals include steel and pig iron (with a carbon content of a few percent) and alloys of iron with other metals (such as stainless steel).

The mantle is the mostly-solid bulk of Earth's interior. The mantle lies between Earth's dense, super-heated core and its thin outer layer, the crust. Mantle is not a rock but a layer of earth.