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| A broken flint pebble from Crystal Palace Park |
Following on from my investigation of the geology and historic architecture in and around Wadsley Park Village, my next trips coincided with a week spent in London – to help my 92 year old mum after she had come out of hospital, having fallen over and broken her hip when scarifying the lawn.
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| Crystal Palace Park |
Having completed essential tasks such as mowing the lawn, watering various plants, clearing up fallen blossoms, moving potential trip hazards and doing the shopping - while at the same time photographing various listed buildings around West Wickham for the British Listed Buildings website – I set out to explore Crystal Palace Park, with the intention of visiting its ‘dinosaurs’.
The 1921 geological memoir for South London describes the Crystal Palace ridge, along with isolated plateaux of Richmond Park and Wimbledon Common, as being amongst the principal topographic features. Standing at a height of 110 metres above sea level, this high point is now emphasised by the Crystal Palace transmitter, which can be seen from miles around.
This high ground in the Tertiary strata is formed by the Claygate Member, the sandy upper part of the London Clay Formation, which differs considerably from the lower part - a heavy, blue/grey homogenous clay that I remember from digging trenches for foundations in north London, when working as a builder’s labourer before studying geology at Nottingham University.
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| A topographic map of the Crystal Palace ridge |
Growing up in South London, I clearly recall the topography formed by the various river terraces that drop down from Clapham Common and the steep slope that rises up to Upper Norwood but, apart from my brief exploration of Wimbledon Common the year before, I had never given much consideration to London’s geology.
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| A walkway cover in flint pebbles |
Having had a quick look at the various terraces, which are the remains of the Crystal Palace that burned down in 1936 and will be described later, I was very interested to discover that the various walkways are covered in gravel that is composed largely of various sized pebbles of black flint.
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| The geology around Crystal Palace Park |
I later learned that the highest part of the Crystal Palace ridge is covered by Quaternary gravel of an unknown age which, according to the geological memoir, consists mainly of Chalk flints, with a large proportion of Tertiary pebbles and Greensand chert, which are derived from the south and probably represent the outwash from snow or ice covered ground that was beyond the limits of the Pleistocene ice sheet.
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| Flint pebbles from Crystal Palace Park (21 mm diameter coin) |
Having picked up a few pebbles to add to my rock collection, I then made my way down to the Information Centre, where I came across a large boulder of Precambrian Lewisian gneiss – one of the ‘Millennium Rocks’ from the coastal village of Lochinver in north-west Scotland, which were given to the borough of Bromley in 2000.
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| A boulder of Lewisian gneiss |
Although this rock is obviously not an example of the local geology, every student of geology in the UK is taught about the Lewisian gneiss in the north-west of Scotland – which very few will ever visit – and it was therefore a very pleasant surprise to discover this.
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| A detail of the Lewisian gneiss |
cool.
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