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A Rare Phenomenon EarthCache

Hidden : 03/28/2013
3 out of 5
2.5 out of 5

Size: Size:   other (other)

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Geocache Description:

This is a relatively simple "mystery" Earthcache on the Purple "Lough Avalla Farm" National Loop. I do not tell you what the phenomenon is, it is your task to tell me :-)

The Hike

Take the purple national "farm" loop from the advised parking and trail head. The loop is about 8km long and can be taken within 3 hours if you are in a hurry. Do reserve 5 hours for taking pictures, having lunch, admiring views etc. or even more if you take small kids. There are a few tricky spots on the loop but these are provided with handy railings. All in all very little change elevation, but some extensive portions of limestone pavement walk, these can get dangerously slippery after rain or while raining. Your kids will love meeting and watching the farm animals, especially goats and sheep. Apart from farm animals you can spot badgers, foxes etc. This loop is one of the best marked in Ireland, it does not let you guess where to go next as long as you have at least 100m visibility. It is marked strictly clockwise, so it should be taken clockwise, unless you know it very well.


I marked the cache as kids friendly, because it is a very well maintained path through an eco-friendly farm, still you should know yourself if your child has enough stamina, food & drink, experience, proper boots and garment etc. to take about 8km on mixed farmland, woodland, limestone pavement etc. terrain.


You will go past a holly well which is the only stage in SaaX's "Take nothing but memories". The holy well is always worth a stop..

The Earth cache

Exactly at the cache coords you will locate a rare geological phenomenon. It is a specimen of differential chemical weathering (erosion).
In order to log this cache you need to tell me
  1. what it is, [explain and describe in your own words and try to classify in geological terms]
  2. estimated dimensions: length (l), width (w), thickness (t) of the upper part, average height (h) XOR (exclusive OR) depth (d) from ground level,
  3. which geological formation is exposed at the GZ and how old approximately in millions of years this formation is.
  4. Try and explain in your own words why this is an example of differential erosion rather than an erratic.------

Becuase several cachers had issues with q3, I decided to link a valuable resource (Geoscientific Guide to the Burren) that will help with this Earthcache in general and with q3 in particular..


I do not mind if the estimates are not very accurate but I should like to see that you looked at the real thing out there and did your own thinking eventually supported by reading on limestone pavements, karstic phenomena, differential erosion etc. BTW there are many Earth Caches on kartsic phenomena, the closest two are The Burren and Ailwee Cave
There is one in France (Provence) - Doline - that is on differential erosion in karstic landscapes, but this one is substantially different.
My own Coole Turlough is on HYDROLOGICAL aspects of karstic landscapes endemic to British isles, prominently appearing in Irish mid-West, so it is unrelated and won't help you with this one. Still the basic chemical principle behind all kartsic phenomena including this one is the same, so looking up any of the above for the basics won't hurt.

Other instructions

To provide answers, you can contact me through my geocaching profile or - if you want to support your explanations with pictures, gpx tracks or other attachments  - you can write directly to


  • include your answers in the log,
  • upload any pictures of the phenomenon to the log.
All logs that will violate the above restrictions will be immediately deleted without warning.

I hope that you have enjoyed the looped walk, measuring and thinking as thoroughly, as I have.. :-)

Additional Hints (Decrypt)

1) Hfr lbhe bja obql: Gur jvqrfg fcna bs lbhe fgergpurq nezf vf nobhg gur fnzr nf lbhe urvtug. 2) Gur sbezngvba vf ABG gur Oheera Sbezngvba; hfr Trbfpvragvsvp Thvqr gb gur Oheera.

Decryption Key


(letter above equals below, and vice versa)