Define soil and discuss the factors responsible for its formation? [5 MARKS]
Define soil and discuss the factors responsible for its formation? [5 MARKS]
Definition ; 1 Mark
Factors and its explanation : 1 Mark each
The upper layer of earth in which plants grow, a black or dark brown material typically consisting of a mixture of organic remains, clay, and rock particles.
The factors or processes that make soil are:
• The Sun: The Sun heats up rocks during the day so that they expand. At night, these rocks cool down and contract. Since all parts of the rock do not expand and contract at the same rate, this results in the formation of cracks and ultimately the huge rocks break up into smaller pieces.
• Water: Water helps in the formation of soil in two ways.
(i) Water could get into the cracks in the rocks formed due to uneven heating by the sun.
(ii) Flowing water wears away even hard rock over long periods of time. Fast flowing water often carries big and small particles of rock downstream. These rocks rub against other rocks and the resultant abrasion causes the rocks to wear down into smaller and smaller particles. The water then takes these particles along with it and deposits it further down its path. Soil is thus found in places far away from its parent-rock.
• Wind: Strong winds also erode rocks down. The wind also carries sand from one place to the other like water does.
• Living organisms also influence the formation of soil. The lichen grows on the surface of rocks. While growing, they release certain substances that cause the rock surface to powder down and form a thin layer of soil.
Definition ; 1 Mark
Factors and its explanation : 1 Mark each
The upper layer of earth in which plants grow, a black or dark brown material typically consisting of a mixture of organic remains, clay, and rock particles.
The factors or processes that make soil are:
• The Sun: The Sun heats up rocks during the day so that they expand. At night, these rocks cool down and contract. Since all parts of the rock do not expand and contract at the same rate, this results in the formation of cracks and ultimately the huge rocks break up into smaller pieces.
• Water: Water helps in the formation of soil in two ways.
(i) Water could get into the cracks in the rocks formed due to uneven heating by the sun.
(ii) Flowing water wears away even hard rock over long periods of time. Fast flowing water often carries big and small particles of rock downstream. These rocks rub against other rocks and the resultant abrasion causes the rocks to wear down into smaller and smaller particles. The water then takes these particles along with it and deposits it further down its path. Soil is thus found in places far away from its parent-rock.
• Wind: Strong winds also erode rocks down. The wind also carries sand from one place to the other like water does.
• Living organisms also influence the formation of soil. The lichen grows on the surface of rocks. While growing, they release certain substances that cause the rock surface to powder down and form a thin layer of soil.
