Contour Lines and Their Intersection

Contour lines are lines that indicate the elevation of a particular area when drawn on a topographic map. These lines are drawn at a certain interval known as the contour interval. The contour interval is the vertical distance between two consecutive contour lines. When the contour lines intersect, it indicates a change in elevation.

Possible Cases of Intersection

1. Vertical Difference
When contour lines intersect at a perpendicular angle, it indicates a vertical difference between the two lines. This means that there is a sudden change in elevation between the two lines. This can occur in cases such as cliffs, steep slopes, and vertical drops.

2. Cave
Contour lines can intersect in the case of a cave when the cave is located on a slope. The contour lines above the cave will intersect with those below the cave, indicating a change in elevation due to the presence of the cave.

3. Overhanging Difference
When contour lines cross each other but do not intersect at a perpendicular angle, it indicates an overhanging difference. This means that the ground is sloping downwards in one direction and upwards in another direction. This can occur in cases such as overhanging rocks and cliffs.

Correct Answer and Explanation

The correct answer is option 'B' which states that contour lines can intersect in the case of 2 and 3 only. This means that contour lines can intersect in the case of a cave and overhanging difference but not in the case of vertical difference. Contour lines do not intersect at a perpendicular angle in the case of overhanging difference, which rules out option 1. On the other hand, vertical difference only occurs when contour lines intersect at a perpendicular angle, which rules out option 3. Therefore, the only possible cases of intersection are a cave and overhanging difference, which is option 2.

Option B