Which of the following statements regarding Barchan is/are correct? 1. It is a crescent shaped mound of sand, which is deposited by the wind blowing constantly from one direction in a desert. 2. The windward side has a convex steep slope with maximum height at the centre. 3. Two ends of Barchan are called horns and point opposite to the direction the wind blows. Select the answer using the code given below:
Understanding Barchan Sand Dunes
Barchans are a specific type of sand dune found in deserts. They are formed by wind blowing predominantly from one direction. Let's analyze the given statements about Barchans to determine which ones are correct.
Statement 1: Shape and Formation
The first statement says: "It is a crescent shaped mound of sand, which is deposited by the wind blowing constantly from one direction in a desert."
- Barchans are indeed characteristically crescent-shaped dunes.
- Their formation requires a consistent wind direction.
- They are landforms created by wind deposition of sand in arid or semi-arid environments like deserts.
Based on the characteristics of Barchans, this statement accurately describes their shape and the condition required for their formation.
Statement 2: Slopes and Height
The second statement says: "The windward side has a convex steep slope with maximum height at the centre."
- The windward side of a Barchan is the side facing the incoming wind. This slope is typically gentle and convex due to the sand being pushed up by the wind.
- The leeward side (or slip face) is on the downwind side and is much steeper, often approaching the angle of repose for sand (about 30-34 degrees). This slope is concave.
- The maximum height of a Barchan is generally located at the crest, near the center of the dune.
The statement incorrectly describes the windward side as having a steep slope; the windward slope is gentle. The steep slope is the leeward side. Therefore, this statement is incorrect.
Statement 3: Horns Direction
The third statement says: "Two ends of Barchan are called horns and point opposite to the direction the wind blows."
- Barchans have two "horns" at their ends, which extend downwind.
- These horns are formed because the edges of the sand supply are thinner and move faster than the bulk of the dune.
- Since they extend downwind, the horns point in the same direction the wind is blowing, not opposite to it.
This statement is incorrect because the horns of a Barchan point in the direction the wind blows, following the path of less resistance for the sand at the dune's edges.
Conclusion on Barchan Statements
Based on the analysis:
- Statement 1 is correct.
- Statement 2 is incorrect (windward slope is gentle, leeward is steep).
- Statement 3 is incorrect (horns point downwind).
Therefore, only statement 1 is correct.
The correct option is the one stating that only statement 1 is correct.
Revision Table: Barchan Characteristics
| Characteristic | Description |
|---|---|
| Shape | Crescent-shaped (or half-moon shaped) |
| Formation Condition | Consistent wind direction, limited sand supply |
| Windward Slope | Gentle, convex slope facing the wind |
| Leeward Slope | Steep, concave slope (slip face) on the downwind side |
| Horns | Two points extending downwind from the center |
| Movement | Migrates slowly in the direction of the wind |
Additional Information on Sand Dunes
Sand dunes are fascinating landforms created by the action of wind (aeolian processes) in areas with a sufficient supply of sand and appropriate wind conditions. Besides Barchans, other common types of sand dunes include:
- Transverse Dunes: Long ridges perpendicular to the prevailing wind direction. Formed where sand is abundant.
- Longitudinal Dunes (Seif Dunes): Long ridges parallel to the prevailing wind direction. Formed in areas with strong, consistent winds and limited sand.
- Star Dunes: Large, star-shaped dunes with multiple arms radiating from a central peak. Formed in areas where wind directions are variable.
- Parabolic Dunes: U-shaped or hairpin-shaped dunes, often found in coastal areas or regions with some vegetation. Their horns point upwind (opposite to Barchans).
The shape and type of a sand dune depend on factors such as wind speed, wind variability, sand supply, and vegetation cover. Studying sand dunes helps us understand desert environments, wind erosion and deposition, and even extraterrestrial landscapes (dunes exist on planets like Mars).
Similar Questions
Consider the following characteristics of a grassland :
1. An extensive area of mid latitude grasslands are devoid of trees and shrubs.
2. The climate is characterised by hot summers, cold winters and relatively low rainfall occurring mainly in spring and summer.
3. In humid parts, grasses grow to a meter or more in height.
On the basis of the above characteristics, select the correct grassland from the options given below:
Which of the following statements regarding earthquakes is/are correct?
1. The point on the Earth's surface directly above the focus is called the epicentre of the earthquake.
2. Earthquakes generate Primary and Secondary waves that radiate outward from the earthquake focus.
3. Deep-focus earthquakes are likely to cause more damage than shallow-focus earthquakes.
Select the answer using the code given below:
Which of the following statements regarding Earth's internal structure is/are correct?
1. The oceanic crust is heavier than the continental crust.
2. Most of the Earth's internal heat is contained within the mantle.
3. Large convective cells in the crust circulate heat and drive plate-tectonic processes.
Select the answer using the code given below:
Identify the land biome on the basis of the given characteristics:
1. Their climates are characterised by high rainfall and temperatures that vary from cold to mild.
2. These forests contain primarily deciduous trees - including maple, oak, hickory and beechwood.
3. Raccoons, opossums, bats and squirrels are found in the trees.
Select the correct land biome from the options given below:
Which one of the following is not an igneous rock?
Which of the following statements is/are correct?
1. Hypocenter is the point on the surface of the Earth, nearest to the focus.
2. Velocity of earthquake waves is higher in denser materials.
3. P waves move faster and are the first to arrive at the surface of the Earth.
Select the correct answer using the code given below:
Which one of the following is the lowermost/innermost intrusive igneous rock?
Which one of the following is found in the innermost part of the Earth?
Consider the following statements :
1. Rocks do not remain in their original form for long and undergo transformation.
2. Transformation of rocks is caused by weathering, erosion and metamorphic action.
Which of the statements given above is/are correct?- Which one of the following is likely to be the most prevalent form of weathering in hot-tropical desert areas?
Important Questions from Geomorphology
Sandstone is an example of:
Which of the following isnota Metamorphic rock?
Which of the following is NOT a sedimentary rock?
- Identify the third layer of soil from top.
The down fold in a rock is known as a/an:
