i think it is an opening
Hachured contour lines on a topographic map indicate a depression or a hole in the ground. They are lines that have small perpendicular lines extending from them, pointing inward toward the depression or lower elevation area they represent.
There will be a continuous line describing the perimeter of the depression, and along this line will be short spikes extending inwards; indicating that there may be a cliff there. Ordinarily, they will be marked in black, but on a glacier, they will be shown in blue. This convention should be indicated on the legend of the map.
topographical map.
its called an index or index conotour line and is every fitth line on a topographic map.
The heaviest contour lines on a topographic map indicate the highest elevation on the map. These lines represent the peaks of mountains, hills, or other elevated land features.
Hachured contour lines on a topographic map indicate a depression or a hole in the ground. They are lines that have small perpendicular lines extending from them, pointing inward toward the depression or lower elevation area they represent.
circles inside circles with teeth inside the last circle
What I need is a topographic map!
The small loop on a topographic map typically represents a closed depression or sinkhole. The dot indicates the highest point within a closed contour on the map.
a topographic map
I believe it is a Thematic map.
A pit on a topographic map represents a depression or low area in the landscape, typically surrounded by higher elevation contours. Pits can be natural features, such as sinkholes or craters, or man-made features like quarries or mines. They are represented by concentric contour lines that indicate the depth and shape of the depression.
A topographical map.
A depression is shown by contour lines with small marks pointing toward the lowest point of the depression.
Topographic map
There will be a continuous line describing the perimeter of the depression, and along this line will be short spikes extending inwards; indicating that there may be a cliff there. Ordinarily, they will be marked in black, but on a glacier, they will be shown in blue. This convention should be indicated on the legend of the map.
Hachured contour lines are contour lines with ticks pointing downslope that indicate a depression on a topographic map.