Question

What type of wind erosion leaves pebbles and boulders behind? A) deflation C) abrasion B) loess D) sandblasting

Short answer

Deflation (A) leaves pebbles and boulders behind.

Step-by-step solution

Understand Wind Erosion

Wind erosion involves the movement of soil and rock particles by the wind. It can change landscapes by removing lighter particles and leaving heavier materials behind.

Define Deflation

Deflation refers to the removal of loose, fine-grained particles by the wind, leaving heavier particles such as pebbles and boulders behind. This process helps create desert pavements.

Define Abrasion

Abrasion involves the scraping, scratching, dragging, or rubbing of rock surfaces by more substantial particles, like sand, carried by the wind. It doesn't specifically leave larger materials behind.

Define Loess

Loess refers to a deposit of wind-blown silt and is not directly related to leaving pebbles and boulders. It usually contributes to forming fertile soil.

Define Sandblasting

Sandblasting is the process where sand grains carried by wind wear down surface materials through abrasion but, like abrasion, does not involve leaving larger particles behind.

Determine the Correct Answer

The definition of deflation fits the description of a process that leaves behind larger particles like pebbles and boulders because it removes smaller, lighter materials. Therefore, the correct choice is A) deflation.

Key concepts

Deflation

Deflation is a fascinating natural process where wind plays a significant role in shaping the landscape. Imagine the wind as a giant broom sweeping away loose and fine-grained particles like dust, sand, and silt from the surface of the land. This process gradually removes these lighter particles and often leads to the exposure of larger and heavier materials like pebbles and boulders.
Deflation is particularly common in desert environments where vegetation is sparse, and the soil is dry and loose.
Some interesting points about deflation include:

• It can create hollowed-out depressions known as deflation hollows or blowouts.
• Deflation is a key step in forming desert pavements, which are flat, stony surfaces consisting of closely packed pebbles and rocks.
• The process often leads to the lowering of the land surface as lighter materials are continuously removed over time.

In summary, deflation is an essential geological process that helps shape arid landscapes by leaving behind larger particles after finer materials have been whisked away by the wind.

Abrasion

Abrasion is another fascinating aspect of wind erosion, though it differs significantly from deflation. Think of abrasion as nature's own sandblasting technique. In this process, wind-driven particles such as sand grains act like tiny chisels, constantly scraping and wearing down rock surfaces they come into contact with.
This process can lead to the smoothing and polishing of rocks and can even carve out unique shapes over time.
A few noteworthy aspects of abrasion are:

• It primarily affects exposed rock surfaces, especially those directly in the path of strong winds.
• Abrasion is more about the alteration of surfaces rather than the removal of materials, making it distinct from deflation.
• The effects of abrasion are more evident in areas with strong, persistent winds and a plentiful supply of sand.

Abrasion doesn't leave larger particles like pebbles behind. Instead, it alters existing surfaces through continual wearing and etching.

Desert Pavement

Desert pavement is a remarkable feature often found in arid regions, including deserts. It results from the process of deflation, where the wind removes finer particles leaving behind a mosaic-like layer of larger rocks and pebbles.
This layer forms a characteristic flat and nearly continuous surface, much like a natural stone mosaic covering the landscape.
Some important points to understand about desert pavements are:

• They can protect the underlying soil from further erosion by minimizing the exposure of loose particles to the wind.
• Desert pavements tend to be very stable and can remain unchanged for long periods unless disrupted by human or animal activity.
• The formation of desert pavements is indicative of a mature landscape where wind erosion has occurred over a prolonged period.

In essence, desert pavements serve as a protective crust, helping to preserve the underlying substrate while providing a unique habitat for certain desert flora and fauna.