Which of the following statements is/are true? i. Contour lines cross valley line at 90°. ii. Contour lines cross ridge line at 90°. iii. Contour lines are widely spaced where ground has steep slope.
Contour: Contour lines are the lines joining the points of equal elevation on the ground surface. Contour interval on map sheet denotes the vertical distance between two successive contour lines. Characteristics of the contour lines are: ● Two contour lines do not intersect each other except in the case of an overhanging cliff and a cave penetrating a hill. ● All lines close themselves within the map boundaries or outside it. Contours lines cross a valley or ridgeline at 90°. ● If the contour lines are very close to each other, this indicates a steep slope. ● If the contour lines are at a very large distance to each other, this indicates a gentle slope. ● If the closed lines have higher elevation in the center then it represents the hill or mountain. ● If the closed line have increasing elevation as we move away, then it represents a pond or a depression in the ground profile. ● The direction of the steepest slope is along the shortest between the contours.