| Mountains are built up, but also disappear over long periods of time. Hence, mountain
belts on earth show a great variety of age. Sometimes, a mountain region is formed by several orogenies.
Generally, young mountains are the highest and steepest (e.g. the Andes, the Himalaya), while older formations no longer uplift, but are only
eroding.
Mountains are often built up later than their rocks were formed. There
are different periods of orogenesis throughout the history of the earth.
In the Overview
of the major orogenic phases diagram, you can see the main orogenic
phases of the last 2000 million years and examples of mountain ranges.
On the map, the formation age of selected mountain chains is shown. Click
on legend icons to turn layers on and off.
Find out for the Alps, Ural, Himalaya, Appalachian Mountains, Kaukasus,
and Atlas...
- if the mountains are younger than 250 million years and indicate the
name of the orogenesis.
- which mountains still lie at an active plate margin.
- which two of the mountain chains might be the lowest in elevation
and explain the reason for your assumption.
Solution
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