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The wall of rocks and debris directly in front of you
was deposited by the Rhone Glacier sometime between 1640 and 1740*. Looking out
across the plain you can see other, similar walls. The glacier ice transports
huge amounts of rocks and debris. This material is left behind alongside the
glacier as a lateral moraine, or as an end moraine at the glacier's face. When
the ice has melted away, the debris travelling on top of the glacier is left on
the ground. Typical moraine material consists of a varied mix of rough
boulders, rocks, debris, sand and extremely fine loam, a result of the grinding
forces exerted on sand and gravel caught between the glacier and the bedrock on
which it travelled.
Near the glacier, the young moraines are still bare and
instable. But as soon as the first debris-covering pioneering plants have
arrived, their roots begin to hold the loose material together, collecting fine
soil, and stabilizing the moraine. As time goes by, new and more demanding
species join these specialists, and the plant cover begins to thicken.
At
this point, the vegetation has had about three hundred years to develop, and
for individual plant species to take hold in their favourite locations. The
Marsh violet and the Marsh marigold can be found in the more humid hollows, the
«Alpenrose» and the Paradise lily on the dry slopes, while the
Common heather and the Trailing azalea prefer the very dry, wind-scoured top
where nutrients are scarce. Finally, the Mountain houseleek, whose fleshy
leaves can hold its water supply, manages to survive on just a few tiny crumbs
of soil.
* The marker by the
trailside bearing the year 1818 no longer corresponds to the latest research
findings. |
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The Paradise lily prefers dry slopes |
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The Creeping avens is a
pioneering plant with long stolons. |
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Each end moraine bears witness
to an earlier
position of the glacier.
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The strong shoots of the Glacier crowfoot hold and
stabilize the debris. |
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