What makes a mountain

1
How do mountains grow?
In the broadest sense mountains develop where
tectonic forces promote surface uplift. Climate
shapes an uplifting surface into its various
forms through its effects on glaciers, rivers and
atmospheric circulation. In the following slides
we will explore some of the process that shape
the Worlds highest mountains and explain why they
develop where they do.
2
A quarter of the Earths land mass is considered
mountainous 18 of the worlds population
inhabits mountainous regions.
Figure 1
World Health Organization (2005) Human Health
Impacts from Climate Variability and Climate
Change in the Hindu Kush-Himalaya Region,
Regional Office for South-East Asia, Mukteshwar,
pp 2-12.
3
Where mountains grow
Figure 2
The Worlds highest mountain ranges all developed
at the edges of continental plates. These plates
move(d) against each other, colliding, subducting
(sinking), pulling apart etc. This plate motion,
and other interactions, can cause rock to uplift.
The uplifted rock is then sculpted into mountains
by processes such as landsliding and river
incision.
4
As the Earths surface uplifts, rivers cut down
forming valleys and ridges. In general the
long-term rate of river incision is similar to
the long-term rate of rock uplift fast rock
uplift deep narrow valleys, slow or no rock
uplift broad low angle valleys.
5
River incision creates the base-level to which
hillslopes react. Where river incision is very
fast hillslopes react by landsliding.
Photo USGS
6
Sometimes the landslides are so big they lower
the mountain top. These really big landslides are
called Sackungen.
7
In our experiments we grow mountains that look
like Mt. Blanc in France (on the right), but at a
much smaller scale (see below).
In the laboratory we speed up the process that
form mountains so that we may better understand
how they evolve. A mountain like Mt Blanc takes
millions of years to grow, we grow our mountains
in 1-day.
8
Figure 3
Our experimental mountains most closely resemble
those that form when continental plates split
apart, e.g. the Wasatch mountains shown above. As
the Earths surface splits apart near vertical
faults form (above right). During fault movement
the Hanging wall moves down and the Footwall
moves up. Mountainous topography forms in the
Footwall as rivers and landslides sculpt the
surface.
9
Our experimental apparatus is an erosion box in
which two opposing panels are able to slide
independently, so simulating base-level fall or
rise across an emerging topography. Rainfall is
generated by an ultra-fine misting apparatus
mounted overhead.
Please click here if you want to watch a video of
one of our experiments. In this video you will
see 3 views Two from front and back plus an
overhead view.