The Rhenish Massif is a geologic massif

Massif

In geology, a massif is a section of a planet's crust that is demarcated by faults or flexures. In the movement of the crust, a massif tends to retain its internal structure while being displaced as a whole...

 in western Germany

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, eastern Belgium

Belgium

Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...

, Luxembourg

Luxembourg

Luxembourg , officially the Grand Duchy of Luxembourg , is a landlocked country in western Europe, bordered by Belgium, France, and Germany. It has two principal regions: the Oesling in the North as part of the Ardennes massif, and the Gutland in the south...

 and northeastern France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

.

The Rhenish Massif consists of the Belgian and French Ardennes

Ardennes

The Ardennes is a region of extensive forests, rolling hills and ridges formed within the Givetian Ardennes mountain range, primarily in Belgium and Luxembourg, but stretching into France , and geologically into the Eifel...

, the German Eifel

Eifel

The Eifel is a low mountain range in western Germany and eastern Belgium. It occupies parts of southwestern North Rhine-Westphalia, northwestern Rhineland-Palatinate and the south of the German-speaking Community of Belgium....

 and east of the river Rhine the Sauerland

Sauerland

The Sauerland is a rural, hilly area spreading across most of the south-eastern part of North Rhine-Westphalia, in parts heavily forested and, apart from the major valleys, sparsely inhabited...

 and Siegerland

Siegerland

The Siegerland is a region of Germany covering the old district of Siegen and the upper part of the district of Altenkirchen, belonging to the Rhineland-Palatinate adjoining it to the west.Geologically, the Siegerland belongs to the Rheinisches Schiefergebirge...

. The Mosel

Mosel

Mosel may mean the following:* Moselle , a European river, named Mosel in German* Mosel , a German appellation, formerly known as Mosel-Saar-Ruwer** Mosel wine, wine produced in the region...

 and Hunsrück

Hunsrück

The Hunsrück is a low mountain range in Rhineland-Palatinate, Germany. It is bounded by the river valleys of the Moselle , the Nahe , and the Rhine . The Hunsrück is continued by the Taunus mountains on the eastern side of the Rhine. In the north behind the Moselle it is continued by the Eifel...

 hills form its southwestern part, the Westerwald

Westerwald

The Westerwald is a low mountain range on the right bank of the River Rhine in the German federal states of Rhineland-Palatinate, Hesse and North Rhine-Westphalia. It is a part of the Rhine Massif...

, Lahn

Lahn

The Lahn River is a -long, right tributary of the Rhine River in Germany. Its course passes through the federal states of North Rhine-Westphalia , Hesse , and Rhineland-Palatinate ....

-Dill area and the Taunus

Taunus

The Taunus is a low mountain range in Hesse, Germany that composes part of the Rhenish Slate Mountains. It is bounded by the river valleys of Rhine, Main and Lahn. On the opposite side of the Rhine, the mountains are continued by the Hunsrück...

 occupy the southeastern part. The massif is divided in two by the Middle Rhine

Middle Rhine

Between Bingen and Bonn, Germany, the Rhine River flows as the Middle Rhine through the Rhine Gorge, a formation created by erosion, which happened at about the same rate as an uplift in the region, leaving the river at about its original level, and the surrounding lands raised...

 Valley, a UNESCO World Heritage area.

Geology

Geologically the Rhenish Massif consists of metamorphic rock

Metamorphic rock

Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...

s, mostly slate

Slate

Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. The result is a foliated rock in which the foliation may not correspond to the original sedimentary layering...

s (hence its name), deformed and metamorphosed

Metamorphism

Metamorphism is the solid-state recrystallization of pre-existing rocks due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids. Mineralogical, chemical and crystallographic changes can occur during this process...

 during the Hercynian orogeny (around 300 million years ago). Most of the massif is part of the Rhenohercynian zone

Rhenohercynian Zone

The Rhenohercynian Zone is in structural geology a fold belt of west and central Europe, formed during the Hercynian orogeny . The zone consists of folded and thrusted Devonian and early Carboniferous sedimentary rocks that were deposited in a back-arc basin along the southern margin of the then...

 of this orogeny, that also encompasses the Harz

Harz

The Harz is the highest mountain range in northern Germany and its rugged terrain extends across parts of Lower Saxony, Saxony-Anhalt and Thuringia. The name Harz derives from the Middle High German word Hardt or Hart , latinized as Hercynia. The legendary Brocken is the highest summit in the Harz...

 further east and Devonian rocks of Cornwall

Cornwall

Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...

 (southwestern England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

).

Most rocks in the Rhenish Massif were originally sediments, mostly deposited during the Devonian

Devonian

The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...

 and Carboniferous

Carboniferous

The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...

 in a back-arc basin

Back-arc basin

Back-arc basins are geologic features, submarine basins associated with island arcs and subduction zones.They are found at some convergent plate boundaries, presently concentrated in the Western Pacific ocean. Most of them result from tensional forces caused by oceanic trench rollback and the...

 called the Rhenohercynian basin. In some places in the Ardennes, even older rocks of Cambrian

Cambrian

The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...

 to Silurian

Silurian

The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5 Mya , to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...

 age crop out as massifs overlain by Devonian slates. These older rocks form smaller massifs of their own (Stavelot

Stavelot Massif

The Stavelot Massif is a geological massif in the Belgian Ardennes . Most of the massif crops out in Belgium, but a small part lies across the border with Germany....

, Rocroi, Givonne and Serpont). In the eastern Rhenish Massif some very limited outcrops in the Sauerland show rocks of Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

 and lower Siliurian age. Further Ordovician rock exposures are part of the southern Taunus

Taunus

The Taunus is a low mountain range in Hesse, Germany that composes part of the Rhenish Slate Mountains. It is bounded by the river valleys of Rhine, Main and Lahn. On the opposite side of the Rhine, the mountains are continued by the Hunsrück...

.

The second rock type are Tertiary

Tertiary

The Tertiary is a deprecated term for a geologic period 65 million to 2.6 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary...

 and Quaternary

Quaternary

The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...

 igneous rock

Igneous rock

Igneous rock is one of the three main rock types, the others being sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava...

s, which most prominently occur in the Vulkaneifel, the Westerwald and the Vogelsberg

Vogelsberg

Vogelsberg is a municipality in the Sömmerda district of Thuringia, Germany....

.