Wednesday, 10 August 2022

A Recce of Lyme Park - Part 2

 
A view of Lyme Park mansion and The Cage

Shortly after we had started our recce of Lyme Park, for a possible field trip with the Sheffield U3A Geology Group, Stewart and I met one of the National Trust staff and, when discussing our proposed route with her, we looked up at the ridge to the west and didn’t fancy walking up it. 
 
The landscape to the east of Cage Hill

Having looked at the glacial erratics on Cage Hill, we traversed a vale formed in the underlying mudstones and then started the ascent up the dip slope of the Woodhead Hill Rock to Locality 4. Here, in lumps of sandstone that have made their way to the surface, there are apparently examples of weathered feldspar, which leave pits in the surface, but we didn’t see these. 
 
A view of The Cage from Lantern Wood

By the time we had walked up the hill to Lantern Wood, after stopping a couple of times, I was in need of a rest and Stewart was in some distress. Although many of our group are in their 70s, our walks often contain moderately steep sections that are tackled without much fuss, but we both thought that this was harder than we were usually accustomed to. 
 
The Lantern

After a good rest, we continued through Lantern Wood until we encountered the Lantern, a Grade II* Listed belvedere, which was built to take advantage of the fine views over the Cheshire Plain that can be seen from here.  
 
An exposure of the Rough Rock in an old quarry
 
The next stop was an old quarry on the Rough Rock, the uppermost named sandstone formation in the Millstone Grit Group. We had seen a very coarse pebbly variety during our previous field trip to Roundhay Park in Leeds but the sandstone here, which is iron stained along the joints, does not have these pebble beds. 
 
Large scale cross-bedding in the Rough Rock

The sandstone seen in this quarry is generally very massive, with large scale cross-bedding and wedge shaped units, but there are thinner flaggy beds from which I collected a greyish medium/coarse grained specimen with mica clearly visible on the bedding plane. 
 
A specimen of flaggy Rough Rock

Looking at it with a hand lens, the mineralogy is predominantly quartz, with a moderate amount of pink/white degraded feldspar, minor weathered iron bearing minerals and occasional dark red/purple clots, which could be the heavy mineral garnet. 
 
A view to the Cheshire Plain beyond The Cage

Continuing up the path, the guide directed us to Locality 5, where we were supposed to find a small block of sandstone in the path, which contained an impression of a fossil plant that is probably Lepidodendron; however, as with the fossil plants at Locality 1, we could not find anything and carried on to the top of the ridge, from which there are further views of the Cheshire Plain. 
 
Scarp and vale topography on the skyline

A little further south, a series of ridges can be seen in the skyline, where sandstones alternate with softer, siltstones and mudstones to form the scarp and vale topography that is a characteristic of the Upper Carboniferous rocks in Britain. 
 
A glacial erratic of volcanic origin in the path

Having reached the high point of our walk, without really seeing that much geology, we headed down the path back towards the car park. The path is well worn and eroded and, before long, we began to encounter small glacial erratics embedded in the ground, which provide evidence of the vertical extent of the ice sheet. 
 
A small metamorphosed volcanic tuff erratic
 
Once we got our eye in, we could see many examples of the green metamorphosed volcanic tuff from the Borrowdale Volcanic Group in the Lake District, which weathers to a much lighter colour than the fresh but still has a distinctly green tinge. 
 
Various pieces of glacial erratics
 
With the itinerary for the day now completed, Stuart and I came to the conclusion that this particular walk from Rocky Rambles in the Peak District was definitely a walk for ramblers, with a bit of geological interest added, rather than a geological field trip that involved a reasonable walk. 
 
A view of Lyme Park mansion and The Cage

At the end of the day, without actually walking that far, we both felt quite tired and, even though we had paid to see Lyme Park mansion in our entrance fee, we didn't think that we would do this justice at the end of a long day and therefore decided to set off home.
 
The walk around Lyme Park

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