A26: Petrology is a branch of geology that deals with the study of rocks. The term is derived from the Greek words “Petrus” (rock) and “Logos” (study).
Q27: Name three major active volcanoes mentioned in the text.
A27: Three major active volcanoes mentioned are Mount Vesuvius, Mt. Stromboli, and Mt. Etna in Italy.
Q28: Why are sedimentary rocks important for natural resources?
A28: Sedimentary rocks are important sources of natural resources like coal, oil, and natural gas.
Q29: What is the estimated age of the oldest sedimentary rocks in the world?
A29: The oldest sedimentary rocks in the world have been identified in Greenland and are estimated to be 3.9 billion years old.
Q30: What type of rock was used to build the Taj Mahal?
A30: The Taj Mahal in India was built with white marble, which is a metamorphic rock.
Q31: What are the layers of soil in order from top to bottom?
A31: The layers of soil from top to bottom are:
- O-Horizon (Humus)
- A-Horizon (Top Soil)
- E-Horizon (Elevated layer)
- B-Horizon (Sub-soil)
- C-Horizon (Parent Rock)
- R-Horizon (Parent Rock)
Q32: What is the O-Horizon in a soil profile?
A32: The O-Horizon, also known as Humus, is the top layer dominated by organic material such as leaves, needles, twigs, moss, and lichens.
Q33: What is found in the B-Horizon of soil?
A33: In the B-Horizon or Sub-soil, you can find accumulations of iron, clay, aluminum, and organic compounds.
Q34: How long does it typically take for soil to become well matured?
A34: It takes about 3000 years for soil to become well matured.
Q35: How does soil formation time differ in wet tropical areas compared to mild climates?
A35: In wet tropical areas, soil formation is faster, taking up to 200 years to form one cm of soil, compared to 200-400 years in mild climates.
Q36: What are the three types of sedimentary rocks mentioned in the text?
A36: The three types of sedimentary rocks mentioned are:
- Organic Sedimentary Rocks
- Mechanical Sedimentary Rocks
- Chemical Sedimentary Rocks
Q37: What is dynamic metamorphism?
A37: Dynamic metamorphism is a process where changes in rocks are mainly caused by high pressure.
Q38: How does granite transform into gneiss?
A38: Granite transforms into gneiss through dynamic metamorphism.
Q39: What are evaporates in the context of sedimentary rocks?
A39: Evaporates are chemical sedimentary rocks formed by the precipitation of minerals from water, usually through evaporation of chemical-rich solutions.
Q40: What is the composition of the earth’s crust (Lithosphere)?
A40: The earth’s crust (Lithosphere) is composed of rocks.
Q41: How many different types of minerals are estimated to be found on the earth’s surface?
A41: It is estimated that there are 2,000 different types of minerals found on the earth’s surface.
Q42: What percentage of the basic minerals are commonly found all over the earth?
A42: Only 8 basic minerals out of the 2,000 different types are commonly found all over the earth.
Q43: Why is soil called the ‘skin of the earth’?
A43: Soil is called the ‘skin of the earth’ because it forms on the surface of the earth.
Q44: What are the major agents of soil erosion?
A44: The major agents of soil erosion are running water and wind.
Q45: Name three types of soil erosion mentioned in the text.
A45: The three types of soil erosion mentioned are:
- Sheet erosion
- Rill erosion
- Gully erosion
Q46: What type of soil is ideal for growing cotton?
A46: Black soil is ideal for growing cotton.
Q47: Which soil is suitable for plantation crops like tea and coffee?
A47: Laterite soil is suitable for plantation crops like tea and coffee.
Q48: Why are desert soils generally infertile?
A48: Desert soils are generally infertile because they are porous and saline.
Q49: How does soil act as a natural filter?
A49: Soil acts as a natural filter of water and purifies it.
Q50: What is the significance of soil in land management and ecosystems?
A50: Soil supports ecosystems and plays an important role in land management.
