The Beauty of Geological Maps

I have always loved maps, ever since trying to follow our routes in a car using my parents one inch to one mile map of the local. Proper maps get in as much information as possible, and here the Ordnance Survey maps of the UK are some of the best. I cannot say that about many road atlases, which show nothing but main roads and have no beauty to them.

However nothing beats the beauty of a geological map. The first was William smith’s of 1815, which is remarkably accurate for THE first attempt. He got so much of the geology of England pretty well summed up. He marked the whole of the Fylde around Blackpool, Lancashire as Permo-Triassic (actually he called it New Red Sandstone) despite there being almost no rock exposures there. He worked it out by superb geological intuition. This picture does not do it justice to the map/

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My favourite is the geological map of Anglesey produced by Rev John Henslow in 1822. This is found in his Memoir of the geology and each copy was hand-cloured. This picture does not do it justice for the sharp colours. In 1831 Darwin used this map when he was with the Rev Adam Sedgwick. I found the map remarkably accurate considering

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I must leave the human past and consider this beautiful map of the geology of the USA.

We have the swirls of the Appalachians which used to join on to Britain with a variety of rocks Palaeozoic and older; The boring (to me!) strata of the Piedmont in the south which is so much younger; ancient shield rocks around Wisconsin; the extensive unfolded Mesozoic and later strata of the prairies, only relieved by fossil dinosaurs, the window of the Black Hills with rocks up 3.3 billion years, (and NRA members with holsters). Last, and most recent is the Western third, which are still very much tectonically active. Those with a good eye will make out the line of the Cascade volcanoes, and the broken up (Basin and Range) nature of Nevada. To look at the west most simply, there is almost a straight North-South line where the Rockies rise out of the Prairies. Looking at the map one can see how the geology has influenced the topography

 

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To those who thirst for more, then read John Macphee Annals of a Former World.  It is compulsory reading for some beginning geology students in the USA as it is so readable – and informative

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