Today, we are looking at,Bunter beds.
These are sandstone deposits containing rounded pebbles.They can be found in Warwickshire, Cheshire, Staffordshire, Shropshire, Nottinghamshire, Yorkshire, Devon and Dorset in England.
They are thought to be alluvial deposits and, judging from the rounding of the mainly quartzite pebbles, to have resulted from prolonged transportation in a large and turbulent river, resulting in powerful abrasion The river carried pebbles with it, when the pebbles stopped moving they became lodged in the sand surrounding them and cemented into place as the sand turned to stone..
The deposits in the English Midlands are thought to have been transported in this way northwards from Brittany, France.
This supposed river has been called the "Budleighensis", after the Devon village of Budleigh Salterton, a site where such deposits were discovered. The depositions took place in the lower Triassic period, around 220 million years ago.
The name "Bunter" derives from the German term "Buntsandstein", "bunt" meaning "variegated" or "colourful", referring to the colour of the sandstone deposit, which varies from reddish to greenish.
This sandstone is widespread across central Europe, notably in the Black Forest and Odenwald region of Germany, as well as the Vosges Mountains in northeastern France.
1. Now you have arrived at the GZ please explain what you have found.
2. Describe the structure of the sandstone that you are looking at.
3. In the pebble bed you will observe many different pebbles, there are some shiny milky white/purple pebbles, what rock are they formed of?
4. The pebble bed is formed in sandstone, what is another name that the pebble beds are known by?
5. Having carefully observed and touched the pebbles, please describe their texture and also explain how they have got like this
6. Having observed lots of different coloured pebbles in the bed, please find 4 different ones and list the colours in your email
7. In order to record your visit to this unique location please post a photo of you or your GPS at the GZ, this is totally optional. As this pebble bed is approximately 250 million years old please do not move or take any of the pebbles or damage the location by exploring up the bank
Please email me the answers, to the above questions, at the same time you log the cache. Thank you.