TEST OF PRACTICAL KNOWLEDGE QUESTION (a) Outline... | WAEC SSCE - Geography - 2016

Question 1 Report

TEST OF PRACTICAL KNOWLEDGE QUESTION

(a) Outline three differences between deflation and abrasion
(b) Using specific examples, describe the mode of formation of a deflation hollow

Answer

(a) Three differences between deflation and abrasion

Deflation	Abrasion
It is the lifting and removal of loose, fine, dry particles (sand and dust) by the wind.	It is the wearing away of rock surfaces by the impact of wind-driven sand particles.
It requires no tools; the wind simply blows the loose material away.	It uses sand grains as tools to scrape, polish and grind the rock.
It produces features such as deflation hollows and desert pavements.	It produces features such as zeugen, yardangs, rock pedestals (mushroom rocks) and ventifacts.

(b) Mode of formation of a deflation hollow

A deflation hollow is a shallow depression on the desert floor produced by wind deflation.

In arid regions the surface is covered with loose, dry, unconsolidated sand and dust particles that are not held together by moisture or vegetation.
Strong winds blowing over the surface pick up and carry away these fine, loose particles in a process called deflation.
As the loose material is continually removed, the ground level is progressively lowered and a depression begins to form.
Deflation continues until the wind reaches the water table (where the sand becomes damp and can no longer be lifted) or a layer of coarse pebbles too heavy to move, forming a desert pavement. At this point deepening stops.
The resulting shallow, enclosed depression is the deflation hollow. A well-known example is the Qattara Depression in Egypt.

Answer Details

(a) Three differences between deflation and abrasion

Deflation	Abrasion
It is the lifting and removal of loose, fine, dry particles (sand and dust) by the wind.	It is the wearing away of rock surfaces by the impact of wind-driven sand particles.
It requires no tools; the wind simply blows the loose material away.	It uses sand grains as tools to scrape, polish and grind the rock.
It produces features such as deflation hollows and desert pavements.	It produces features such as zeugen, yardangs, rock pedestals (mushroom rocks) and ventifacts.

(b) Mode of formation of a deflation hollow

A deflation hollow is a shallow depression on the desert floor produced by wind deflation.

In arid regions the surface is covered with loose, dry, unconsolidated sand and dust particles that are not held together by moisture or vegetation.
Strong winds blowing over the surface pick up and carry away these fine, loose particles in a process called deflation.
As the loose material is continually removed, the ground level is progressively lowered and a depression begins to form.
Deflation continues until the wind reaches the water table (where the sand becomes damp and can no longer be lifted) or a layer of coarse pebbles too heavy to move, forming a desert pavement. At this point deepening stops.
The resulting shallow, enclosed depression is the deflation hollow. A well-known example is the Qattara Depression in Egypt.

TEST OF PRACTICAL KNOWLEDGE QUESTION (a) Outline three differences between deflation and abrasion (b) Using specific examples, describe the mode of formatio...