Answer:
Explanation:
A deep, long and wide trough or basin with very steep concave high walls at its head as well as in sides is known as Cirque. It is a bowl-shaped valley or basin that is formed at the head of a glacier. Cirques are formed by the processes of glacial erosion and weathering. The formation of cirque starts with the accumulation of snow in a mountainous area. Over time, this snow gets compressed to form ice. The weight of the ice causes it to flow downhill, and as it moves, it erodes the rock underneath, creating a concave shape.

Features of Cirque:
- Bowl-shaped valley or basin
- Steep concave high walls
- Formed at the head of a glacier
- Formed by the processes of glacial erosion and weathering

Formation of Cirque:
Cirques are formed by the processes of glacial erosion and weathering. The formation of cirque starts with the accumulation of snow in a mountainous area. Over time, this snow gets compressed to form ice. The weight of the ice causes it to flow downhill, and as it moves, it erodes the rock underneath, creating a concave shape. As the glacier moves down the slope, it continues to erode the rock, deepening the cirque and widening it into a U-shaped valley.

Importance of Cirque:
Cirques are important features of the landscape because they provide evidence of past glaciation. They also provide habitats for a variety of plants and animals, which have adapted to the harsh conditions of the alpine environment. In addition, cirques are popular tourist destinations because of their scenic beauty and the recreational opportunities they offer, such as hiking and skiing.

Conclusion:
In conclusion, a cirque is a deep, long and wide trough or basin with very steep concave high walls at its head as well as in sides. It is formed by the processes of glacial erosion and weathering and is an important feature of the landscape.