Landforms from contours

Landforms from contours:

• Conical hill: rises evenly from the land around, with a narrow top: concentric contours at regular spacing.
• Plateau: a wide, flat-topped highland with steep sides: contours close at the margins, and the innermost contour enclosing a wide area.
• V-shaped valley (in mountains, cut by a river): V-shaped contours whose innermost contour has a narrow gap and the lowest value; values rise outward. The V points upstream, towards higher ground.
• U-shaped valley (cut by a glacier, with a wide flat floor and steep sides): the innermost contour has a wide gap.
• Gorge (deep, narrow valley where the river cuts down faster than sideways): very closely spaced contours with a narrow innermost gap.
• Spur (a tongue of high land sticking out into lower land): V-shaped contours the other way round: the arms point to higher ground and the point of the V towards lower ground.
• Cliff: contours running very close and merging into one.
• Waterfall: contours merging where they cross a stream; rapids above or below it are shown by contours spaced a little apart across the stream.

Drawing a cross-section (a side view of the ground along a line):

• Draw a straight line AB across the contours.
• Lay the edge of a paper strip along AB and mark where each contour crosses it, with its value.
• Choose a vertical scale (such as ½ cm = 100 m) and draw parallel horizontal lines as long as AB, one for each contour value, numbered from the lowest.
• Lay the strip along the bottom line, matching A and B, and from each mark draw a perpendicular up to the line of its height.
• Join the points smoothly.

Example (new): on a map you see a circle of contours marked 400, 420, 440 and 460 m, very close on all sides, with a large flat space inside the 460 m line. That is a plateau, not a conical hill, because its top is wide.