Saturday 6 November 2021

A Walk From Firbeck to Stone

 
A quartz vein in a pebble of brecciated quartzite

Leaving Firbeck, having had a good look at its vernacular architecture and St. Martin’s church, I headed north out of the village along New Road until I came to a public footpath and headed off towards Stone – a hamlet that I had never visited before.
 
The footpath from Firbeck to Stone

The path passes to the north of small patches of Quaternary sediments that are marked as till and glaciofluvial deposits on the geological map and, although not of sufficient concentrations to be marked on the map, I soon encountered a scattering of pebbles of various colours and sizes in the fields next to the path.
 
Following my recent investigation of the area around Kiveton Park and Todwick, there was an abundance of brown, highly polished pebbles of what I would now tentatively identify as Carboniferous sandstone – having broken open some of these with my Estwing hammer.
 
A pebble of Carboniferous sandstone

On this occasion, I was mindful not to burden myself by collecting an excess of specimens and just took a few photographs of some of the larger pebbles that I found, with only a handful being taken home for further investigation.
 
Another pebble of Carboniferous sandstone

A dark red pebble that I found is obviously not local, as is the brown pebble that looks like a Carboniferous sandstone at first glance, but which is actually a breccia with veins of quartz that would undoubtedly be classified as a quartzite.
 
A pebble of dark red quartzite

When looking closer with my hand lens at all of these rocks, the highly polished nature of all the pebbles makes it difficult to assess their mineralogical composition and an examination with a petrological microscope is really needed to identify them.
 
A brecciated quartzite pebble with a quartz vein

Of the four pebbles that I collected, two are faceted on all sides, indicating that they are ventifacts which have been turned over on at least one occasion since their deposition - enabling the sandblasting of all surfaces during cold and arid conditions.
 
Rocks collected on the way to Stone

No comments:

Post a Comment