Colour values from Abraham Gottlob Werner's Nomenclature of Colours as revised by Patrick Syme (1821), the book Darwin carried aboard the Beagle, sampled from a scanned first edition for Nicholas Rougeux's digital edition. The original book is public domain; the digitisation is his work. Mountain range and colour pipeline from the OIMU Colour Wheel by David Calum Millar, after oklch.com.