On a topographic map, a knoll is represented as a distinct, isolated circular contour line, often referred to as a ring contour.
What is a Knoll?
A knoll is essentially a small, rounded hill or a natural elevation, often described as a hump or bump in the landscape. They are typically smaller than a mountain but larger than a mere mound. Understanding how they appear on maps is crucial for navigation and terrain interpretation.
How Knolls Appear on Maps
Maps use contour lines to depict elevation and terrain. Each contour line connects points of the same elevation, providing a two-dimensional representation of a three-dimensional landscape. For a knoll, these lines form a concentric circle or an almost circular shape. The innermost circle represents the highest point of the knoll, with subsequent outer circles indicating decreasing elevation as you move away from the summit.
Key characteristics to look for when identifying a knoll on a map:
- Circular Shape: The defining feature of a knoll on a map is its closed, often circular or elliptical contour line.
- Concentric Rings: Multiple contour lines will form rings within each other, similar to the rings of a tree trunk. The smallest, innermost ring indicates the peak of the knoll.
- Spot Elevation: Sometimes, a specific spot elevation (a number indicating the exact height) might be placed at the center of the innermost ring, marking the knoll's precise summit.
- Steepness Indication: The spacing of the contour lines around the knoll indicates its steepness. Closely spaced lines suggest a steep slope, while widely spaced lines denote a gentler incline.
Typical Locations of Knolls
Knolls are frequently found in specific geographical contexts:
- On or near the summits of larger hills and mountains: They can appear as minor peaks or subsidiary bumps alongside a main summit.
- Along ridges and spurs: These are elevated areas extending from a main mountain or hill, where knolls might appear as small, isolated rises along the elevated strip of land.
Understanding Contour Lines
Interpreting contour lines is fundamental for understanding any landform on a topographic map, including knolls. For a deeper dive into reading topographic maps and their various symbols, resources like the U.S. Geological Survey (USGS) provide excellent guides.
Example Characteristics of a Knoll's Map Representation:
| Feature | Description |
|---|---|
| Shape | Closed, generally circular or elliptical contour lines |
| Arrangement | Concentric rings, with the smallest ring indicating the highest point |
| Spacing | Close lines mean steep slopes; wide lines mean gentle slopes |
| Numbering | Contour lines are often numbered to show their elevation above sea level |
| Context | Often appears on larger hills/mountains, ridges, or spurs |
