Please note that this is an Earthcache and you must
complete the tasks listed below BEFORE logging the
cache.
The ideal place to log this cache is from the Car Park waypoint
which is wheelchair friendly but also feel free to include
photographs of them from more imaginative places as well. Pictures
from canoes, boats, divers and the bridge would be great.
This picture was taken 1hr after high water on a Neap tide with
the water flowing into the loch. The Falls are quite tame here -
see if you can visit when they are roaring!
A tidal race (or rapid) occurs at a location where a large
volume of water passes through a constriction resulting in the
formation of waves, eddies and hazardous currents. The constriction
is normally a passage where the sides narrow, or an underwater
obstruction (such as a reef or abupt change in the depth of the
seabed). At the Falls of Lora, there are both. The bridge is built
at the narrowest place at the mouth of Loch Etive and all the water
has to squeeze through this constriction so it moves very quickly.
However another feature which emphasises the effect is that just
underneath the bridge there is a 1.2 m shelf in the underlying
Basalt rocks which is higher on the Loch Etive side. As the tide
rises and falls water flows into or out of Loch Etive over this
shelf it often creates spectacular waves and currents which make it
a playground for canoeists.
The water level in the open sea rises and falls due to the
influence of the moon & the sun - this movement is called a
Tide. At certain times the moon & sun combine to create very
big tides called 'Spring' and at others they oppose producing
smaller 'Neap' tides. So the water at the seaward side of the
Connel Bridge rises and falls and pushes water in and out of Loch
Etive
Because of the constriction, the water level in Loch Etive lags
behind the level at the seaward side leading to some strange
effects. Firstly, there is a period when the sea tide is dropping
but water is still flowing inland at the bridge. Similarly, when
the tide in the open sea is rising, it takes some time to come up
to the level of the water which is still escaping from the loch.
This means that at the bridge the ebb tide (falling) starts 2 hours
10 minutes after high water Oban and the flood (rising) starts 2
hours fifty minutes after low water Oban. These two times are
called slack water because it is not flowing into or out of the
Loch.
The best times to see really good waves are in the last 2 hrs
before Low water on a Spring tide so try and plan your visit for
then by referring to tide tables - either on the internet or in
small booklets available in bookshops in the Oban area. The volume
of water flowing in and out of the Loch is huge - typically
27,000,000 cubic metres or tonnes move in and out of Loch Etive on
every Spring tide.
Good luck and enjoy this powerful natural phenomenum.
To log this cache please e-mail the following details to
RattyinStirling
or through the link to my profile on the listing page
1. To log the cache please submit a picture of the Falls from the
Car Park waypoint as in the picture above. Please include the
precise time at which the picture was taken. The picture of the
waves from that location should show clearly what state they were
in. If you wish you can include your GPS unit in the picture
showing the coordinates
2. Include any other pictures from different locations with the GPS
coordinates of the place from where you took the pictures? This
task is optional but fun.
3. Refer to Tide Tables and note the time & height of Low &
High water at Oban on the day you observed the falls.
4. Find out if this was a Spring or a Neap tide or somewhere
between them and find out the phase of the moon on the day.
5. Rate the condition of the falls by observing the following
attributes
Speed of flow - 1 for still, 2 for slow, 3 for fast.
Height of waves - 1 for flat, 2 for small waves, 3 for big breaking
waves.
Noise - 1 for silent, 2 for can just hear sound, 3 for loud.
Add up your total out of 9.
When you have contacted me with your answers and I have responded
to them then please enter your log on the cache site and upload
your pictures.
I received three emails at the same time on this one so
FTF took a bit of detective work but eventually goes to
NotoriousNRE - well done!