Step 7 | Click the Bookmarks button and choose Camp David.

Step 8 | Click the Map Layers button.

Step 9 | Click the eye icon to the right of the layer name USA Topo Maps.

Question | Why does this area not have concentric circles or parallel lines close together?

Note that some topo lines are thicker than others and are called index contours. These index contours have elevation values periodically along their lengths, which other contour lines do not have.

Question

Step 7 | Click the Bookmarks button and choose Camp David.

Step 8 | Click the Map Layers button.

Step 9 | Click the eye icon to the right of the layer name USA Topo Maps.

Question | Why does this area not have concentric circles or parallel lines close together?

Note that some topo lines are thicker than others and are called index contours. These index contours have elevation values periodically along their lengths, which other contour lines do not have.

BlackTom AI · Accepted Answer

To understand why the map area lacks concentric circles or tightly spaced lines, we need to interpret contour lines onTopographic maps. 
Option A: 'This area is very steep.' If the terrain were very steep, contour lines would be drawn close together, indicating a rapid change in elevation over a short horizontal distance. The presence of widely spaced lines would contradict this, so this option describes the opposite situation and is therefore incorrect.
Option B: 'This area is fairly flat.' When land is flat or gently sloped, contour lines are spaced far apart because the elevation changes gradually over a longer distance. The observed spacing aligns with a flatter terrain, making this choice correct. 
Additionally, the note about index contours being thicker with periodic elevation labels helps distinguish elevation changes without implying steepness; their presence simply aids reading the map rather than indicating tight contour clustering. 
In summary, contour line spacing communicates slope: tight clustering signals steep terrain, while wide spacing signals flat or gently sloped terrain, supporting the conclusion that the area is fairly flat.

类似问题

On 21 H/1, the contour interval is different! Check! What is the elevation of the campground on The Lookoff (894063)? (It's on top of the bluff in the picture below)

Consider map sheet 92 G/6. Look at the contours around the UBC campus (around 830570). Also look at the contours around Grouse Mountain (945704). If they had used the 83 C/3 contour interval, what would the result have been?

看看 92 G/6。在夏天，您可以徒步登上松鸡山滑雪山 “cut” 并免费乘坐缆车下山。滑雪山道由黑色虚线表示。滑雪山底部的海拔是多少（944688）？

在 92 G/6 上，Unnecessary Mountain （855769）的前峰海拔是多少？

在 92 G/6 上，弗洛姆山前峰（958692）的海拔是多少？（知道等高线间距后，您可以在 880 m 线以上的每条线上增加米数）

Backpackers, campers, and hikers often use this type of map:

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