Friday, 20 November 2015

Burbage Rocks

A view across a spring line in the Burbage Valley

Various sedimentary structures can be seen at Carl Wark and Higger Tor, in the fallen rocks and when peering out along the crags; however, at Burbage Rocks, the foreset and top set beds - deposited in an ancient deltaic environment - are spectacularly exposed along its length.

Large scale sedimentary structures at Burbage Rocks
Like all the other gritstone edges, it is popular with rock climbers but it is easy to get up close to the vertical crags and look at the rocks in greater detail.

On this occasion, I preferred to see them from the path that runs parallel to the edge and below the blockfield.

In all of the blocks found off the path, there are plenty of opportunities to look at the coarse sandstone - comprising sub-angular grains of quartz, with weathered feldspar and mica - as well as abundant pebbles of vein quartz.

Walking further along the edge, two sets of joints running at right angles to each other are clearly visible – one runs parallel to the edge and the other cuts into the rock face – and in places they are eroded to produce buttress like overhangs that offer a severe challenge to the rock climbers.

Structural geology in the Burbage Valley
It might be easy to miss, when looking at such a spectacular skyline, but the path coincides with a spring line, where the upper leaf of the Chatsworth Grit meets the underlying shale.

Although this natural feature is partially obscured by the path, the occurrence of the springs is marked by a very noticeable change in the vegetation.

In mid-September, both the heather and the  bracken are at the height of their growth and dominate the other plants.

Sphagnum moss, however, is in its element in such boggy conditions and - once you look beneath the distinctive grass like stems of the sporophytes that appear to have died off at this time of the year - it is clearly visible.

Sphagnum moss

With the length of my Geotour around the Burbage Valley being determined by the hourly bus timetable, I could have spent an extra hour exploring an old quarry where millstones were once made and then walked back up to Fox House to have a well earned drink; however, having spent just over 4 hours between arriving and departing, I decided that this 5 mile walk in the Peak District was enough for one day and headed back into Sheffield instead.

Putting my feet up at a traveller's rest in Sheffield