The Story of the Stone Runs
Anyone visiting the Falkland islands must have noticed the long streams of boulders that stretch down from the hillsides.
These vast, yet intricately patterned accumulations of boulders impressed Darwin when he visited on HMS Beagle in 1833-34. He refererred to them as "streams of stones", but it is the vernacular "Stone run" that has become the popular Falklands expression. To a scientist they are periglacial blockfields and blockstreams. The blocks are made up of White Quartzite. Quartzite is a hard rock which was originally pure quartz sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression, tectonic plates moving together or apart and folding the rocks over eons.
The smallest runs are only a metre across whilst the largest are up to four kilometres long and several hundred metres wide.
These landforms were produced thousands of years ago under the very cold conditions of the last Ice Age. They arose as innumerable cycles of freezing and thawing first broke up the rock. As the seasonally thawing ground slowly crept downhill over the deeper layer of permafrost it flowed out onto lower areas to the uncanny flat-topped surface to the bigger accumulations.
Usually, the uppermost boulders have been leached by rainwater and lower down in the stonerun, where the boulders have been protected from the weather, they are stained.
To log this Earthcahe, it would be great (but not essential) if you could take a picture of yourself at this spot with the stone runs in the background. You must also contact me via my username and answer the following simple questions
"1. Looking at the stone runs, consider the variation in size of the boulders as you near the base of the run. What processes over time have led to this ?
Any logs that do not follow the rules of this Earthcache may be considered for deletion. I will of course acknowledge receipt of all e-mails and logging finds