Rhenish Massif

West of the indent of the Cologne Bight it has the Eifel and the Belgian and French Ardennes; east is its greatest German component, the Süder Uplands.Geologically the Rhenish Massif consists of metamorphic rocks, mostly slates (hence its German name), deformed and metamorphosed during the Hercynian orogeny (around 300 million years ago).Most of the massif is part of the Rhenohercynian zone of this orogeny, that also encompasses the Harz further east and Devonian rocks of Cornwall (southwestern England).In the eastern Rhenish Massif some very limited outcrops in the Sauerland show rocks of Ordovician and lower Siliurian age.The volcanic rocks have been linked to a mantle plume that, due to its low density and buoyancy, uplifted the entire region during the last few hundred thousand years, as measured from the present elevation of old river terraces.
Satellite image with outlines (grey-drawn outline) of the Rhenish Slate Mountains (green trees). Above left the mouth of the Rhine into the North Sea.
Geological sketch of the Rhenish Massif
Großer FeldbergElevationGermanyBelgiumLuxembourgFranceNorth Rhine-WestphaliaRhineland-PalatinateParent rangeCentral UplandsOrogenyVariscan (Hercynian)Rock age(s)DevonianCarboniferousRock typeGermanmassifCologne BightArdennesSüder UplandsHunsrückWesterwaldTaunus MountainsMiddle RhineRhine GorgeUNESCO World HeritageMoselleLuxembourgishmetamorphic rocksslatesdeformedmetamorphosedHercynian orogenyRhenohercynian zoneCornwallEnglandback-arc basinRhenohercynian basinCambrianSilurianStavelotOrdovicianTaunusTertiaryQuaternaryigneous rocksVulkaneifelVogelsbergmantle plumesea level (NN)High EifelVulkan EifelAhr HillsZitter ForestFore-EifelMoselle EifelSouth EifelWest EifelSchnee EifelSchneifelBelgian EifelRur EifelHigh FensBingen ForestIdar ForestLützelsoonOsburger HochwaldSchwarzwälder HochwaldSoonwaldArdey HillsIserlohn HeightsPlackwaldArnsberg Forest Nature ParkEbbe MountainsLenne MountainsSaalhausen HillsRothaar MountainsHochsauerlandKellerwaldWest Hesse HighlandsSiebengebirgeMontabaur HeightsGladenbach UplandsAnterior TaunusHigh TaunusHintertaunusWestern HintertaunusIdstein BasinEastern HintertaunusFliegel, D.