Question

1. Fill in the blanks:

a) Rocks like granite or gneiss in South India give rise to

b) One and the same type of rock gives rise to different types of soils when

the rock is exposed to different

c) To form a thick layer of top soil, it takes thousands of years.

d) For getting higher production, different types of chemical fertilizers and insecticides are used profusely, which leads to the

of soils.

2. Answer in one sentence.

a) Name the factors influencing soil formation.

b) When does one type of rock give rise to different soils?

c) What is biotic material?

d) What is humus?​

Answer 1

Answer:

Weathering is a key part of the process of soil formation, and soil is critical to our existence on Earth. In other words, we owe our existence to weathering, and we need to take care of our soil!

Many people refer to any loose material on Earth’s surface as soil, but to geologists (and geology students) soil is the material that includes organic matter, lies within the top few tens of centimetres of the surface, and is important in sustaining plant growth.

Soil is a complex mixture of minerals (approximately 45%), organic matter (approximately 5%), and empty space (approximately 50%, filled to varying degrees with air and water). The mineral content of soils is variable, but is dominated by clay minerals and quartz, along with minor amounts of feldspar and small fragments of rock. The types of weathering that take place within a region have a major influence on soil composition and texture. For example, in a warm climate, where chemical weathering dominates, soils tend to be richer in clay. Soil scientists describe soil texture in terms of the relative proportions of sand, silt, and clay, as shown in Figure 5.14. The sand and silt components in this diagram are dominated by quartz, with lesser amounts of feldspar and rock fragments, while the clay component is dominated by the clay minerals.