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Loch Earn, Perthshire
In the west of Strathearn
lies the stretch of water known as Loch Earn. The deepest part (87m) is located
near the western end. It is 10.5 km from east to west and at it's widest
is 0.8 km. Lochearnhead is situated at its
western end of the Loch and St. Fillans
village at the eastern. From here the River Earn flows east out of the Loch,
down through Strathearn and joins the River Tay Estuary 75 km away.
The Loch basin was dug out by the enormous erosional power of ice during
the glacial periods of the last 2million years.
Loch Earn is unusual in having
it's own 'tidal system'. In fact these are not true tides but is
seiching. (A true tide is driven by the sun and moon). As a result
of the persistent prefailing wind blowing along the Loch there is stress
applied to the water surface. This causes a slight slope on the Loch! As
with all damped mechanical systems, applied pressure can result in an oscillation
called a seiche. In the case of Loch Earn this has a period of 16
hours. The water moves back and forth along the Loch - not in a raging torrent,
of course - but the effect can be observed and measured. The currents can
result in complex turbulance as an upper warmer layer of water mixes with
the lower cooler water near the Loch bottom.
Other fresh water bodies which experience this effect ( seiches )
are Lake Geneva, Lake Garda, Lake Erie and Lake Baikal.
Loch Earn is a centre for both fishing and water-sports: water skiing, canoeing
and sailing. |
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