Puddingstone is one form of what is generally known as sarsen, but with coarser and more pronounced constituent parts than the better-known sarsens of, for example, Stonehenge. It is a conglomerate sedimentary rock composed of rounded flint pebbles cemented together by a younger matrix of silica quartz.
The flints were eroded from their surrounding chalk beds some 56 million years ago and were transported by water action to beaches, where they were rounded by wave erosion and graded by size. A lowering of sea levels and general drying during a brief arid period drew out silica from surrounding rocks into the water immersing the flint pebbles. Further drying precipitated the silica which hardened around the pebbles, trapping them in the matrix.
This was then broken up into blocks by the freeze-thaw action of the Ice Age less than two million years ago, and these blocks were carried into valleys by the torrents of melt water, undergoing further erosion.
It is thought that large numbers of these Puddingstone boulders were later moved into strategic positions to be used as way-markers by prehistoric man.
To claim a find on this cache, you must Message me or email me through my profile with answers to the following questions [and please don't forget to tick the 'send email' box so I can get back to you]:
1 - Where was this particular piece of Puddingstone recovered from, and when?
2 - Examine the boulder, and say what size is the largest individual flint exposed on the surface?
3 - What do you think has given the boulder its generally rounded shape?
4 - What does it measure round the widest part of its girth?
5 - What is the name of the Epoch (NOT the Age or Era) during which the flints were eroded from their surrounding chalk beds?
6 - What were "also trapped in the silica matrix, giving rise to many different hues"?
7 - Where were the surrounding sarsen setts quarried locally?
Please try to include with your log a picture of yourself at the Puddingstone. When examining the stone and taking pictures, please take care not to disturb surrounding planting.
You may log a find without waiting for my reply, but if your answers are not complete or correct your log may subsequently be deleted.