One of
prominent landforms is valleys which are low ground between mountains or
hills or a low passage between higher lands and slope in one direction along
their entire length and tend to be longer than wide. They are created by water
from rain or runoffs. Because water seeks its own level, it always flows downward
towards the lowest ground. As it moves downstream, the water also takes with it
soil, rocks and sediments. Over time, these processes create river valleys. In
the Philippines valleys are usually “V” shaped.
In the
upper river valley, fast-flowing water cuts through a channel, and in the
middle part of the river the water meanders across a broad valley creating a
curved path and in the lower river valley the water flows across a flat plain to
empty into the sea or fan out into a delta. Since time
immemorial river valleys are important to man because the river provides him
water to drink, and the plants, fish and animals that thrive in the river are
his sources for food. Soil and rock sediments that are washed downstream and
along the river provide him with precious minerals like gold and others and the
soil that is washed along the banks makes fertile ground that stimulates
agriculture. It is for these reasons that early civilizations such as Egyptian,
Mesopotamian, Chinese and others developed along great river valleys.
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| A valley in the middle of this picture |
A valley
can have a small or narrow space between two high grounds although its stretch
may be long. It can also be in low elevated area between two high grounds or
high up in the mountain or hills in the middle of a slope. A valley can also be
a tract of land with large area though its high grounds between it are far
apart. Examples are Cagayan Valley and Compostela Valley.
Aside from
the river valley, there are also other kinds of valley. One is the canyon
which is a deep narrow valley. The difference between a canyon and an ordinary
valley is that the higher sides between the low areas of a canyon are very
stiff, such as a cliff. Another is a gorge, a kind of valley which has a
narrower width and deeper than a canyon. The latter is also larger than a
gorge. And there is a ravine which is a type of valley that is shorter
in stretch, narrower in width and shallower in depth than either the gorge or
the canyon. A ravine is found in the forest, hillside, or sloping land. It can
have a small stream or rainwater.
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| The floor of the gorge covered with vegetations |
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| One of the sides or walls of the gorge |
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| Waters falling down into a river valley |
Some valleys
are scenic or a spot for those who love nature adventures. Examples are
the Mangima Canyon in Bukidnon and the Macahambus Gorge in Cagayan de Oro. In addition, some beautiful watercourses such as waterfalls are also within the valleys. Some maps, especially topographic maps that are used by the
military or campers, show valleys and other terrains. Prominent valleys are
also used as point of reference in navigation.
