![Contour map with an example fall line](https://upload.wikimedia.org/wikipedia/commons/8/89/Contour_map_with_an_example_fall_line.jpg)
A fall line refers to the line down a
mountain
A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited Summit (topography), summit area, and ...
or
hill
A hill is a landform that extends above the surrounding terrain. It often has a distinct Summit (topography), summit.
Terminology
The distinction between a hill and a mountain is unclear and largely subjective, but a hill is universally con ...
which is most directly downhill; that is, the direction a ball or other body would accelerate if it were free to move on the slope under
gravity
In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...
. Mathematically the fall line, the
line of greatest slope
Line most often refers to:
* Line (geometry), object with zero thickness and curvature that stretches to infinity
* Telephone line, a single-user circuit on a telephone communication system
Line, lines, The Line, or LINE may also refer to:
Arts ...
, is the negative of the
gradient
In vector calculus, the gradient of a scalar-valued differentiable function of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p is the "direction and rate of fastest increase". If the gradi ...
(which points uphill) and perpendicular to the
contour line
A contour line (also isoline, isopleth, or isarithm) of a function of two variables is a curve along which the function has a constant value, so that the curve joins points of equal value. It is a plane section of the three-dimensional grap ...
s.
![Emmeline-Ragot](https://upload.wikimedia.org/wikipedia/commons/2/24/Emmeline-Ragot.jpg)
In
mountain biking
Mountain biking is a sport of riding bicycles off-road, often over rough terrain, usually using specially designed mountain bikes. Mountain bikes share similarities with other bikes but incorporate features designed to enhance durability and pe ...
, a
trail
A trail, also known as a path or track, is an unpaved lane or small road usually passing through a natural area. In the United Kingdom and the Republic of Ireland, a path or footpath is the preferred term for a pedestrian or hiking trail. Th ...
follows the "fall line" if it generally descends in the most downward direction, rather than traversing in a sideways direction.
A skier is said to be "skiing the fall line" if they are moving generally down, making turns either side of the fall line, rather than moving across the slope.
See also
*
Glossary of cycling
This is a glossary of terms and jargon used in cycling, mountain biking, and cycle sport.
For ''parts of a bicycle'', see List of bicycle parts.
0–9
; 27.5 Mountain bike: A mountain bike with wheels that are approximately in diameter and ...
*
Ridge line
A ridge or a mountain ridge is a geographical feature consisting of a chain of mountains or hills that form a continuous elevated crest for an extended distance. The sides of the ridge slope away from the narrow top on either side. The line ...
*
Topography
Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps.
Topography is a field of geoscience and planetary sci ...
*
Topographic profile
A topographic profile or topographic cut is a representation of the relief of the terrain that is obtained by cutting transversely the lines of a topographic map. Each contour line can be defined as a closed line joining relief points at equal hei ...
References
Mountain biking
Alpine skiing
Trails
Topography
{{Topography-stub