In order to claim a find for this EarthCache you are required to visit the location given, gather some information and send me the answers to the questions below.
Please be aware that there is a footpath but the final the location is a little off actual pathways. There is a sheep track to follow from the footpath about 200m away and it is about half a mile from the nearest parking location, which is about 50m lower than the cache location.
No climbing is required but please only attempt to get to this cache with good footwear and some determination.
You are welcome to log your find and send your answers at the same time. I will read your answer and respond quickly to email and within a few days if you used the message system.
At the location given you will find a wave shaped rock structure about 2m tall where the softer cross bedded lower strata has worn away leaving the harder upper rocks protruding about 1 to 1.5m creating an overhang for about 50m in length.
This shape of rock wave is not uncommon and is created by water or wind weathering and eroding the softer rock and the question I want to ask yourself is how. (not a requirement for logging)
In this instance the softer rock is a cross bedding structure and here is some information about how that happens.
Cross bedding
In geology terms, cross-bedding, also called cross-stratification, is when layering within a stratum is at an angle to the main bedding plane. That is to say a plane of rock which is at a different angle to the horizontal plane that most bedding will be laid at. Imagine a series of card layers cut an laid on top of a desk, then take another series and put them at 45 degree to the horizontal, these are the cross bedding layer.
Looking at the cache background image and the image below you can see the broadly horizontal layers top and bottom and the angled bedding layer sandwiched inbetween, this is what you should be looking for at the cache location.
Cross-bedding forms during deposition on the inclined surfaces of bedding forms such as ripples and dunes; it indicates that the depositional environment contained a flowing medium (typically water or wind).
There are many ways that cross bedding can occur but there are two main reasons. Firstly Cross-bedding can form in a desert environment when sand dunes migrate creating bedding planes that are not horizontal like the main bedding plane. This is a very slow process as the wind piles more and more sand up.
Cross-bedding can also form in river channels when sand bars or ridges are moved downstream. The steady flow of water causes the cross bedding plane to be at an angle to the main bedding plane due to the effect of water flow. This would be a slightly quicker process because of the ability of water to hold and move more material but still takes eons.
In both processes the cross bedding plane takes time for the material to build and build as the pressure, weight and and concretion process creates the rock but unlike rock deposits in slow flowing deltas, the planes of strata are not horizontal, they are angled.
At this particular location not only are the cross bedding layers angled but they are also of a different hardness to the rocks above and below. The different hardness could be a number of reasons, for example;
a) they were laid down with a softer material,
b)they were deposited quickly and didn't have time to set in the same way as horizontal beds might
c)the consistency of material was mixed causing weaknesses in the rock.
Hardness of rocks
A quick note about how to compare rock hardness without doing any damage. Simply rub your thumb on the rock, or pick up a small stone form the ground,the more grains of sand that come off the softer the rock. If it feels smooth, the rock is pretty hard, if you thumb feels to coated like with sugar it's quite a soft rock.
Here are some questions you now need to answer to claim this EarthCache as 'found'
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Please describe the wave shaped rock formation, include details of colour, height, depth and rock structure.
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Please tell me why this rock structure is like this with reference to the hardness of the top strata, cross bedding and base strata.
If you wish to include a photo you may and don't worry about spoilers it's a very easy EarthCache and the location is well worth recording.
Thanks for attempting this cache, I hope you thought it worthwhile and liked the location.
treboR