E. Answer the following in 1-2 each lines.
1.Why is the upper crust also called Sial?
2. Write the composition of the Earth's mantle.
3. What do sedimentary rocks contain?
4. Why are igneous rocks called primary rocks?
5. Give any two uses of rocks.
Answers
Answer:
Ans 1- In geology, the term sial refers to the composition of the upper layer of Earth's crust, namely rocks rich in aluminium silicate minerals. ... The name 'sial' was taken from the first two letters of silica and of alumina.
Ans 2- In terms of its constituent elements, the mantle is made up of 44.8% oxygen, 21.5% silicon, and 22.8% magnesium. There's also iron, aluminum, calcium, sodium, and potassium. These elements are all bound together in the form of silicate rocks, all of which take the form of oxides.
Ans 3- Most sedimentary rocks contain either quartz (siliciclastic rocks) or calcite (carbonate rocks). In contrast to igneous and metamorphic rocks, a sedimentary rock usually contains very few different major minerals. However, the origin of the minerals in a sedimentary rock is often more complex than in an igneous rock.
Ans 4- Igneous rocks are created from the cooling of molten magma/lava. All other rocks are derived from them. Because they form the basis of formation of other types of rocks, igneous rocks are known as the primary rocks.
Ans 5- Making Cement (Limestone) (Sedimentary Origin) Writing (Chalk) (Sedimentary Origin) Building Material (Sandstone) (Sedimentary Origin) Bath Scrub (Pumice) (Igneous Origin)
Answer:
1-the the crust is also called the sea as it comprises of of silicon and Aluminium.
2-this layer is composed mainly of iron silicon and magnesium.
3-these rocks contain not only minerals but also plant and animal remains and for fossils that once lived and died in these places.
4-igneous rocks called primary rocks. these are formed when molten magma cools down and turns into solid rocks.
5-as building materials-granite basalt marble sandstone etc.
as fuel-coal petroleum (mineral oil)