A Geology Field Trip to Chrome Hill

An explanation of the geology at Chrome Hill

Since leading the Sheffield U3A Geology Group to Pontefract in June 2019, although I had kept myself very busy for two months and had travelled widely, I was unable to attend the overnight stay in Whitby and I had missed getting out into the countryside to see some hard rock geology.

The geology around Chrome Hill and Parkhouse Hill

I was therefore particularly looking forward to our trip to Chrome Hill, especially since it had been planned for the previous year and had to be cancelled due to high winds throughout the UK, which I compensated for with a trip to Edensor.

Parkhouse Hill in 1995

Back in 1995, I undertook a survey of the established RIGS (Regionally Important Geological Sites) in the Peak District National Park – to report on their tourism value – and thought that the landform composed of Chrome Hill and Parkhouse Hill was the best that I had seen although, at the time, access to the Duke of Devonshire’s land was denied and I was only able to assess it from afar.

A view from Hitter Hill

Twenty five of us met outside the church at Earl Sterndale, before setting off to Hitter Hill where we made our first stop. With the spectacular fault bound north-west faces of Parkhouse Hill and Chrome Hill in front of us, we learned that the area known as the White Peak occupies an area that was once a large atoll during the Lower Carboniferous Period.

An explanation of our geological map handout

This atoll comprised a central shallow lagoon, with mounds of algal limestone, brachiopods, goniatites, corals and bivalves forming apron reefs and knoll reefs at its edges, flanked by abundant crinoids, and these erosion resistant reefs form dome like landforms.

The White Peak atoll © Trevor Ford

Parkhouse Hill and Chrome Hill are composed of Bee Low Limestone and the embayment to the north-west, which is covered in Namurian Bowland Shale, is considered to be an original feature, as is the fore reef that has bedding planes that are sub-parallel to the south-west facing slopes.

A geological map from the Mercian Geologist

The current limestone topography is thought to be the result of its exhumation from beneath the covering of the softer mudstone, particularly during the Quaternary Period, with modification by local faulting and folding.

A discussion at the base of Parkhouse Hill

The Group then continued down to the base of the south-west face of Parkhouse Hill, where we had a look at an exposure of the fore reef limestone and further discussed its formation before heading up Chrome Hill.

A view from Parkhouse Hill to Dovedale

Taking a break to relate the topography that we had so far encountered to its position on the geological map, we had good views of Parkhouse Hill and Dovedale in the distance, where its apron reefs could be clearly distinguished.

A view from the top of Chrome Hill

At this point, the less able members of the Group took the path that runs below the north-west slope of Chrome Hill, while the others made their way along the ridge, which has some precipitous drops in places.

Massive algal limestone on Chrome Hill

Having negotiated the often difficult terrain along the ridge, without having a good opportunity to study the geology, those of us who took this route stopped briefly to look at an exposure of massive limestone, with no obvious bedding, which constitutes the bulk of the reef.

Steeply dipping beds in the fore reef limestone

Stopping for lunch at a convenient point at the north-west end of Chrome Hill, we then had a look at a good exposure of fore reef limestone before heading north to higher ground where we had a look at a sinkhole, before encountering an outlier of Longnor Sandstone.

The overgrown opening to a sinkhole

With time moving on and a grey sky now threatening rain, we headed east onto the Bee Low Limestone where we crossed the steep sided Dowel Dale, an original ravine in the apron reef and which is flanked by fore reef limestone.

A view down Dowel Dale

Having seen all of the rock exposures on the circular route, we then headed back downslope towards Earl Sterndale, where we unfortunately discovered that the Quiet Woman public house had closed for the afternoon.

The Quiet Woman public house