Just in case you are bursting to know where in England and Wales has the highest natural soil selenium levels - or hundreds of other details - here's a source of answers!
The advanced soil geochemical atlas of England and Wales
The analyses presented in this advanced atlas are for those soil samples collected for the National Soil Inventory (NSI) by the Soil Survey of England and Wales (now the National Soil Resources Institute, Cranfield University, UK) as described in McGrath and Loveland1 (1992) in the original Soil Geochemical Atlas of England and Wales.
The geochemical analyses presented in the original atlas were for a series of 17 elements.
The advanced atlas presents analyses and maps for a total of 53 elements, which includes the original 17 elements.
bgs.ac.uk/gbase/advsoilatla...
It is a large download and takes a while. It is then a large PDF on your computer! Probably would overwhelm most phones.
I came across this after looking specifically for selenium levels. But it has so much more.
Obviously of most interest to gardeners, farmers and those who tend to know where their food comes from.