Rule # 2- Contour lines form
closed circles around the tops of hills and mountains
. Notice that the contours seem to form rings. Inner rings are at higher elevations than outer rings. The innermost rings are the tops of hills.
Are contour lines always closed?
Contour lines always close to form an irregular circle
. Note that sometimes contour lines extend beyond the area on a map so you may not see the entire closed circle.
Why do some contour lines not look closed?
The lines
get closer to each other
as the slope gets steeper. If the area has a gentle gradient, the contour lines are more spread out. If the area is very steep, such as a cliff, the lines may touch, but will never cross over each other.
What does a closed contour line mean?
Contour lines that are relatively close together indicate
a slope that is fairly steep
. Contour lines that are further apart indicates a slope that is relatively flat.
What are the 5 Rules of contour lines?
Rule 1 – every point of a contour line has the same elevation. Rule 2 – contour lines separate uphill from downhill. Rule 3 – contour lines do not touch or cross each other except at a cliff. Rule 4 –
every 5th contour line is darker in color
.
Why can’t contour lines cross?
Contour lines never cross on a topographic map
because each line represents the same elevation level of the land
.
What are the 3 types of contour lines?
Contour lines are of three different kinds. They are
the Index lines, Intermediate lines and the Supplementary lines
.
What is the rule when a river flows over a contour line?
Water always flows downhill perpendicular to the contour lines
. As one proceeds upstream, successively higher and higher contour lines first parallel then cross the stream. This is because the floor of a river valley rises as you go upstream.
How do you tell if contour lines are going up or down?
Remember contour numbering
reads up hill
– in other words the top of the number is uphill and the bottom is downhill. Also remember the closer contour lines are together, the steeper the slope.
Do all contour lines form closed loops?
D. Contour
lines form closed loops around hilltops and depressions
. Elevation numbers on the contour lines indicate whether a feature is a hilltop or depression. If the numbers increase toward the center of the closed loop, the feature is a hilltop.
What is the space between contour lines called?
A contour interval
is the vertical distance or difference in elevation between contour lines. Index contours are bold or thicker lines that appear at every fifth contour line.
How do you get contour lines?
The two ways to establish a contour map are
the cross-section method and the trace contour method
. To use the cross-section method, set a control or reference line at the center of the lot, then lay out and stake a grid; the elevation is determined at each stake in the grid relative to a benchmark.
What is a depression contour line?
A closed contour,
inside of which the ground or geologic structure is at a lower elevation than that outside
, and distinguished on a map from other contour lines by hachures marked on the downslope or downdip side.
What is major and minor contour lines?
The major contour lines at the decades
are logarithmic values that are equally spaced
, and the minor contour lines are linear values that are logarithmically spaced.
Can contour lines cross or split?
1.
Contour lines do not cross each other, divide or split
. 2. Closely spaced contour lines represent steep slopes, conversely, contour lines that are spaced far apart represent gentle slopes.
How do you read contour lines?
Put simply, contour lines
mark points of equal elevation on a map
. If you trace the length of a line with your finger, each point you touch is the same height above sea level. If you were to walk the path of a contour line in real life, you would remain at the same elevation the whole hike, never traveling up or down.
