The Volcanic Isles

Map of the British Isles showing the location of extinct volcanoes (unfilled black circle markers). and bedrock fault lines (orange lines). The coastline is shown in thick black, with a slight dropshadow. The map is coloured in such that the volcanoes are a bright orange/yellow, and the colour moves to a darker purple with distance from a volcano. The same colourscheme is applied at sea, however with reduced opacity. The title text reads: 'The ~~British~~ Volcanic Isles' with subheading: 'Volcanic activity across the British Isles peaked during the Paleozoic (539 to 252 Ma*), with the last significant eruptions occuring during the Paleogene (66 to 43 Ma). *million years ago'. A few key volcanoes are highlighted: Anton Dohrn Seamount (70-41 Ma); Erlend (58 Ma); Rum (60 Ma); Ben Nevis (299 Ma); Dundee Law (415 Ma); Arthur's Seat (299 Ma); Loch Na Fooey (490 Ma); Mynydd y Dref (450 Ma); Bardon Hill (570 Ma); Warboys (300 Ma); Gurnard's Head (400 Ma) — The Volcanic Isles: A brief history of volcanism across the British Isles. Fault lines and extinct volcanoes. The south east seemed to dodge the worst of it. This was made for day 15 of the 2025 #30DayMapChallenge: Fire.

projection	UTM Zone 30N
tools	Python: `matplotlib` for plotting; `geopandas` and `pandas` for wrangling; `scipy` for constructing the `KDTree` used to generate the proximity surface. This was exported and labelling was done, manually, in Inkscape
data	Locations of volcanoes and their approximate ages / date of last eruption came from the List of volcanoes in the United Kingdom, and List of volcanoes in the Republic of Ireland. Fault lines are from the British Geological Survey's 625k bedrock dataset for UK and Northern Ireland, and from the IE GSI Bedrock Geology Datasets 500k Ireland (ROI/NI) for the Republic of Ireland. The coastline is from Natural Earth
font	League Spartan by The League of Moveable Type
comments	The list of volcanoes in the United Kingdom and Republic of Ireland on wikipedia provide an incomplete, and perhaps geologically contentious, list. A several hundred million years old igenous mass does not neccessarily equate with a volcano. A more accurate legend entry might be: 'Sites of volcanic activity' rather than 'Volcanoes'. Noteable omissions from the list: the Pentlands, Ochils, Mull. Oh, and the age of Ben Nevis is off by about 100 ma. A proximity surface was generated to show distance to the nearest volcano, and this was plotted twice: once for on land, and again with reduced opacity at sea. Whilst inspecting the underlying data I spotted, and corrected, the location of Langdale Caldera in the Lake District, whoose longitude was down as East, when it should have been West.
date	15/11/2025