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Snowdon's Summit
In April, snow still lies on the summit of Snowdon, justifying it's
name. A picture of the east-facing wall of the mountain shows that the
summit is the remnant of a huge downfold or syncline. The resistant
Ordovician lavas & ash that form the bulk of the mountain have withstood
the forces of erosion. It is the highest in Wales and reaches 3,560
feet. Snowdon is part of the N.E. to S.W. trending Caledonian fold mountains
that were raised some 300
million years ago. The anticlynes & synclines are similar to those
in the Alps, though less complex. With Snowdon, the downfold forms the
mountain and the adjacent upfolds have been re-moved leaving this mighty
fragment.
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Under the igneous bulk of the mountain is a trough of Cambrian slate which
outcrop to the N.W. and S.E. They are still worked to the south at Blaenau-Festiniog
and to the north at Dinorwic above lakes Padarn and Peris in the Llanberis
valley.
The rock wall in the photograph is at the head of the corrie Cwm Glaslyn.
It was formed by the headward erosion of the glacier, and has left a 1,500
foot precipice above Llyn G1aslyn. The upper slopes of Snowdon are still
being eroded by rock shattering. A long cold winter and precipitation
of over 200 inches a year give ideal conditions for this action.
Bwlchysaethau Arete
This is one of the three aretes which join to form the summit of Snowdon.
It separates the corries Cwm Glaslyn-Llydaw on the left from Cwm Tregalan
on the right. Glaciers in both the corries cut back into the ridge to
make immense precipices on either side. Cwm Glaslyn-Llydaw is the largest
corrie on Snowdon for the glacier was the largest on the mountain. Facing
the N.E., the ice was sheltered from both the sun and the westerly winds
and consequently persisted longer to cut deeper precipices on that side
of the mountain. By contrast, the south-facing corrie Cwm Tregalan,
with its smaller ice load, cut back much less and has left part of the
pre-glacial rounded ridge on that side. This corrie has been free of
ice for much longer and the lower slopes of its precipices are buried
in scree bound by grass. A stream has cut a gorge in the lip of the
cwm, draining away the waters of the lake or tarn, and a small river
system has developed on the corrie's floor.
This magnificent scenery makes the Snowdon area very attractive for
climbing and walking. It was declared a National Park in 1951 to protect
it from unsightly development. The Watkin path is one of the three main
routes up the side of Cwm Tregalan, onto the arete and finally to the
summit. The tourist industry is important here and many hotels cater
for visitors in Llanberis , Beddgelert and Capel-Curig. There is also
an Outward Bound School. The Nature Conservancy controls large areas
to preserve the natural flora & fauna.
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