Blue remembered hills

Into my heart on air that kills
From yon far country blows:
What are those blue remembered hills,
What spires, what farms are those?
A.E. Housman, A Shropshire Lad XL, 1896

I’m going to make a bold statement here, but in my opinion, Shropshire* should be crowned the geological capital of the UK.

*If you don’t know where Shropshire is, I usually describe it as being between Birmingham and Wales…


Ok, so I admit that I’m biased. I am Shropshire born and bred, a proud Salopian.  I credit my upbringing, surrounded by lush lithological riches, as the reason that I became interested in geology and ultimately ended up doing a PhD in Earth Sciences. I’m not Shropshire’s only rock-admirer; the iconic skyline was immortalised in the poems of A.E. Housman and Charles Darwin first practised geological mapping in his native county.

So on what basis do I make my case?

Solid geology of Shropshire, 1:400,000 (shropshire.gov.uk)
Solid geology of Shropshire, 1:400,000 (shropshire.gov.uk). Rocks from 10 out of the 12 geological periods outcrop at the surface, with only the Cretaceous and Tertiary missing.

Diversity
Shropshire’s rocks span 10 of the 12 periods of geological time, charting the tectonic movement of the UK of over 12,000km of latitude during 700 million years. The county’s oldest rocks are Precambrian garnet-mica schists, a fragment of the underlying basement complex. Fast-forward three geological eras to the end of the last Ice Age and the landscape became etched with kettle holes, gorges and morraines. Now think of everything in between; from Ordovician shales, Silurian limestones and New Red Sandstone to andesites, granophyre and dolerite – Shropshire’s got it all.

 

Historical and economic importance
Shropshire has more than earned its place in geological history. The county’s rocks have been involved in many famous geological paradigm shifts, including the recognition of deep time by the ‘father of geology’ James Hutton, the establishment of the Cambrian and Silurian periods by pioneering 19th century geologists Adam Sedgwick and Roderick Murchison, and Charles Lapworth’s subsequent definition of the Ordovician.

The original iron bridge in the eponymous gorge, which is now a UNESCO World Heritage Site. Photo credit: bgs.ac.uk

Most impressively of all, Shropshire’s geology is responsible for creating the birthplace of the industrial revolution. At the end of the Last Glacial Maximum, torrents of icy meltwater scoured the through the land and formed the Ironbridge Gorge. Here, deposits of iron ore, coal and limestone are exposed in one sedimentary succession. The concentration of these raw materials, in addition to plentiful supplies of water, wood and clay, allowed local pioneers to succeed in smelting high quality iron from coke, and to mass produce tiles and bricks.

Fossils
Starting at the (stratigraphic) bottom, Britain’s oldest trilobites were unearthed in 1888 at Comley Quarry. Though today the quarry appears nothing more than an overgrown hollow, the rocks here are used to correlate time with other exposures around the world.

Condover mammoth
The 12,500 year old Condover mammoth was unearthed by a dog-walker in 1986. A model of the skeleton is now on display at the Shropshire Hills Discovery Centre near Craven Arms, Shropshire. Photo credit: Nick Pope

Further riches have been revealed in younger strata. The first British vertebrates (a type of fish) were unearthed in the Ludlow Bone Bed, a thin layer of sediment of Silurian age teeming with fish spines and scales. In the Triassic, north Shropshire was covered by a vast desert, depositing the New Red Sandstone and preserving rare bones and footprints of the reptile Rhynchosaurus. But perhaps Shropshire’s most extraordinary fossil finds occurred in 1986 when a dog-walker discovered the bones of a well-preserved woolly mammoth and remains of its three offspring.

1993
The author (~7 yrs old) on the summit of Caer Caradoc. To the north-east lie the peaks of The Lawley (close) and the Wrekin (horizon), demarking the line of an ancient subduction zone.

Volcanics
Shropshire may be pretty quiet now, but go back 650 – 600 million years and it was the scene of fire, brimstone and furious volcanic activity. The destructive collision of two ancient tectonic plates produced a chain of volcanoes which would have been similar to the modern day Cascades, USA. The eroded remains of the erupted lavas are manifest as the iconic landmarks of The Wrekin, The Lawley and Caer Caradoc.

Shropshire also has more than its fair share of intrusive igneous rocks. Some of the more spectacular examples are the dhustone (dolerite) sill on the summit of Titterstone Clee, the bright pink granophyre at The Ercall quarries and the well-known dolerite peaks of Corndon and the Breiddens.

Passion
The final thing that sets Shropshire apart is its inhabitants’ appreciation of its stunning terrain. The thriving Shropshire Geological Society run a series of winter talks and summer fieldtrips; their website is an excellent place to research a visit (try walking one of the fabulous geo-trails). The Shropshire Hills are designated as an Area of Outstanding Beauty, a fact celebrated by the Shropshire Hills Discovery Centre. A number of sixth-form colleges offer A-level geology and the Field Studies Council runs evening classes on the county’s rocks. Even the self-proclaimed layman could wax lyrical on the beauty of the Long Mynd and the Stiperstones. Shropshire truly is a county of rock-botherers.

ft76
Shropshire has always been a popular destination for university field trips. Here is a group from Bristol (c.1976)!

References
To read more about the geology of Shropshire, try some of these:

– Natural England website – geology of Shropshire
Shropshire Geological Society website – Why is Shropshire important to geology?
– Etheridge, L (2005) Shaping of Shropshire. Shropshire Wildlife Trust
– Toghill P (2006) Geology of Shropshire, 2nd ed

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About Charly Stamper

I’m an ex-experimental petrologist.
I used to make pretend volcanoes; now I work in renewable energy

One thought on “Blue remembered hills

  1. Without doubt Shropshire is a geological wonder, I was born in Shrewsbury, and now live atop the Monkmoor gravel and sand bars of Shrewsbury, laid down by the retreating Welsh glacier. My inspiration to study Geology was the Cambrian/Pre-Cambrian volcanic outcrops that make up the Caradoc and Lawley hills of Church Stretton. This village also has the Long Mynd, a Cambrian sedimentary sequence that has been folded over on itself by later continental collisions. A perfect little village within a wonderful county, well worth a visit.

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