Access and
“Things To Be Aware Of”
Caution! GZ currently
inaccessible at low tide
Logs permitted provided you have completed the tasks
required
Drive to Green Island. Travel along the Southern Scenic Route
through Waldronville, Brighton and on to Taieri Mouth. Cross the
Taieri River bridge and follow the road around to Knarston Park
(~700m after the bridge) where there are toilets and parking.
Completion of this Earthcache requires IDEAL
environmental conditions. Access along the tombolo to Taieri Island
(Moturata) has a brief window of opportunity in terms of
TIME. Best conditions are when ALL THREE of the
following conditions are met:
• VERY LOW TIDE. The lower the tide the more time
the tombolo will be exposed. During neap low tides it may not even
be exposed at all. Consult the ODT for accurate tide times. Or,
check the LINZ tide tables for Bluff and add 1hr 30min as
according to Ocean Fun Publishing to find the low tide time and
height for Taieri Mouth.
• HIGH ATMOSPHERIC AIR PRESSURE. High air pressure
means that there is a tendency for the water to be pushed away from
the high a little and tidal bulging is less. In Otago Harbour low
air pressure can cause tides 20cm higher than normal.
• GOOD WEATHER. Which should coincide nicely with
the high air pressure.
The terrain rating reflects the above. Access to the Taieri
Island itself is not allowed due to it being a wildlife reserve and
breeding ground for the sooty shearwater and blue penguin, however
it seems that walking around the shoreline is okay – but you
probably won’t have time. Finally, tell someone where you are
going, take a phone but don’t rely on it and remember you
don’t have to complete the cache – they aren’t
pokemon.*
No dogs. This cache will be archived if there are any reports
of damage or foolhardiness.
Background
General: A tombolo (Italian, from Latin tumulus –
mound) or sometimes ayre (Old Norse Eyrr – gravel beach) is a
deposition landform in which an island is attached to the mainland
by a narrow piece of land such as a spit or bar. Once attached, the
island is then known as a tied island. Several islands tied
together by bars which rise above the water level is called a
tombolo cluster. Two tombolos form an enclosure called a lagoon
that might eventually fill with sediment.
Tombolo Formation: The act of a spit reaching out to an
island is far from random. By looking at the geomorphology of
tombolos it is possible to understand how they are made. Tombolos
are known to form by wave refraction. As waves near an island they
are slowed down by the shallow water surrounding it. These waves
then refract or “bend” around the island to the
opposite side as they approached. The wave pattern created by this
water movement causes a convergence of longshore drifting on the
opposite side of the island. The beach sediments that are moving by
lateral transport on the lee side of the island will accumulate
there conforming to the shape of the wave pattern. In other words,
the waves sweep sediment together from both sides. Eventually, when
enough sediment has built up the beach shoreline, known as a spit,
will connect with an island and form a tombolo. Tombolos are more
prone to natural fluctuations of profile and area as a result of
tidal and weather events than a normal beach is.
Other Tombolos:There are numerous examples of tombolos in
the world. Some have picturesque medieval villages perched on them,
others form large peninsulas. The Otago Peninsula is joined to the
mainland by the St Kilda Tombolo – Maori are recorded as
having seen this underwater during high tides.
Mt Maunganui
St. Michael's Mount, Cornwall, England
Aupouri Peninsula
Logging
Requirements
0. Preface any email with GC239DQ The Taieri Tombolo in
the subject line and title and clearly note the question number and
answer. Do not wait for a confirmation email to log but be prepared
to be asked for additional information if your answers are
slim.
1. Observe the coastal morphology, the island and the river and
read the information above. Give reasons as to why the narrowest
point of the tombolo is where it is (email answer).
2. At the narrowest point: Measure the width of the tombolo
at this point – paces approx 1m long will save time. Include
this answer and a photo of the task being completed in your log (as
the answer will change continually everyone may as well see
it).
3. Questions: 3a What is the Maori name for Taieri Island?
3b. Give the name of a tombolo not featured on this page. Email
these answers.
4. Final task. Upload a photo showing clearly the tombolo and
the view back to shore (with either you or your GPSr for
authentication).
Acknowledgements and
Sources
Wikipedia article on Tombolos
NZETC hosted article on Lore and History of South Otago Maori
DOC article on Vegetation on Taieri Island
2010
Stegan’s EarthCache Masters Programme
Since it is not very feasible for many NZers to
easily get more than two states for the earthcache.org masters
programme and therefore not get past Bronze I’m running my
own one on a number of Earthcaches that I plan to release this year
(all things being equal) with the following points
system:
5 points: First to find
3 points: 2nd to find
1 point: Logging a find
1-5 points: Special bonus questions.
At the end of 2010, I’ll issue certificates
for 1st, 2nd and 3rd and the first place getter will be awarded a
geocoin. If I feel richer and/or it looks like this is popular
I’ll upgrade the prizes.
Updated information and Leaderboard at: Stegan’s
Earthcache Programme
* “gotta catch ‘em all”
