Rawmarsh and Swinton - Part 2

 

An ochreous deposit below the Abdy Coal

Having parked near to the north-east corner of Victoria Park on Old Warren Vale, we made our way through the plantation towards the northern end of the 200 metre long outcrop of the Abdy Rock, which forms a west-east running ridge through which the cutting was made. 

 

An outcrop of Abdy Rock on Warren Vale

 

Although spring was now well advanced, several outcrops of the northward dipping sandstones could be clearly be seen through the undergrowth, as occasional large projecting blocks of massive sandstone and thinner beds that are sandwiched with siltstone and mudstone – interpreted as crevasse splay deposits, when an ancient river channel overflowed its banks onto the surrounding floodplain. 

 

An exposure of sandstone and siltstone

With my Estwing hammer, I collected a sample of one the more massive sandstone beds, which has been described in the Geological Survey of Great Britain 1947 memoir as a current bedded, often fine grained sandstone that varies greatly in thickness from place to place. My sample is greyish in colour, with pronounced iron banding and also contains flattened ironstone nodules, as seen at Grange Moor Quarry. 

 

A specimen of Abdy Rock

Continuing south along Warren Vale, we encountered progressively older rocks, including black carbonaceous shale, containing what appear to be traces of finely striated fossil plant material, which then pass down into increasingly coaly beds. 

 

A specimen of coaly shale

A little further along Warren Vale, we were both quite taken aback by an exposure of quite massive sandstone, immediately beneath which is what looks like to be a highly fractured seam of bright coal – at the base of which is a flowstone like ochreous deposit, which itself passes down into a weathered grey mudstone. 

 

An exposure of coal and an underlying ochreous deposit

On the geological map, the Abdy Coal is marked as appearing immediately beneath the Abdy Rock and p. 68 of the 1947 memoir further describes the coal seam here as being very poor and split up with dirt partings. 

 

A section at the exposure of the Abdy Coal

 

With no obvious easy access to this very unusual exposure, I didn’t try to obtain a specimen on this occasion and had to settle for a few photographs taken at a distance from the roadside and the nearest vantage point, which Dan and I had scrambled up to.

 

A detail of the Abdy Coal and ochreous deposit