Tag: geography

The igneous rocks are called primary rocks because these were originated first of all rocks during the formation of the upper crust of the earth on cooling, solidification, and crystallization of hot and liquid magmas after the origin of the earth. Thus, all the subsequent rocks were formed, whether directly or indirectly, from the igneous rocks in one way or the other.

• Rocks formed after evaporation of water are called evaporites. Gypsum is an example of evaporites.
  
• Plaster of Paris is manufactured from gypsum and thus it is a secondary product hence cannot be the right answer here.
• Thus option B ie gypsum is the right answer.

• Rocks formed by the cooling of molten rock are called igneous rocks. Among the given options only granite is an igneous rock while rest 3 are sedimentary ricks.
• Hence option C is correct.

The word igneous has been derived from a Latin word 'ignis', meaning thereby fire. The igneous rocks are formed due to cooling, solidification, and crystallization of hot and molten materials known as magmas and lavas. They were originated first of all the rocks during the formation of the earth.

Among the three major types of rock, fossils are most commonly found in sedimentary rock. Unlike most igneous and metamorphic rocks, sedimentary rocks form at temperatures and pressures that do not destroy fossil remains.

Chemical sedimentary rocks are formed by the precipitation of minerals from water. Precipitation is when dissolved materials come out of water. They are typically made up of the minerals halite (calcium chloride, or rock salt) and gypsum (calcium sulfate).

B. Minerals

Native gold is an element and a mineral. It is highly prized by people because of its attractive color, resistance to tarnish, and its many special properties - some of which are unique to gold. Its rarity, usefulness, and desirability make it command a high price. 

The term mineral is sometimes used in reference to natural earth (non-living) resources, and thus, in a non-scientific sense, petroleum resources are mineral resources and deposits of petroleum are often called mineral deposits. Coal, sands, gravel, and such would also be considered a mineral resource in this particular usage, even though coal is a rock, not a mineral, and the others are mixes of multiple minerals and/or rocks and not, strictly speaking, minerals.

Mushroom rocks are formed in deserts. It is an erosional landform of arid regions. The mushroom rocks have a broad upper part and narrow base resembling an umbrella. The erosive power of wind is very high at a certain height from the ground level. The resistant rocks take the shape of a mushroom having large top and a small neck.

Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust. Igneous rocks occur in a wide range of geological settings: shields, platforms, extended crust, basins, and oceanic crust.