Эйфель: Низкогорный регион Германии, Бельгии и Люксембурга.

Low mountain range in Germany

The Eifel (; , ) is a low mountain range in western Germany, eastern Belgium and northern Luxembourg. It occupies parts of southwestern North Rhine Westphalia, northwestern Rhineland Palatinate and the southern area of the German speaking Community of Belgium. The Eifel is part of the Rhenish Massif; within its northern portions lies the Eifel National Park. The Eifelian stage in geological history is named after the region because rocks of that period reach the surface in the Eifel at the Wetteldorf Richtschnitt outcrop. The inhabitants of the Eifel are known as Eiflers or Eifelers.

The Eifel lies between the cities of Aachen to the north, Trier to the south and Koblenz to the east. It descends in the northeast along a line from Aachen via Düren to Bonn into the Lower Rhine Bay. In the east and south it is bounded by the valleys of the Rhine and the Moselle. To the west it transitions in Belgium and Luxembourg into the geologically related Ardennes and the Luxembourg Ösling. In the north it is limited by the Jülich Zülpicher Börde. Within Germany it lies within the states of Rhineland Palatinate and North Rhine Westphalia; in the Benelux the area of Eupen, St. Vith and Luxembourg. Its highest point is the volcanic cone of the Hohe Acht (746.9 m). Originally the Carolingian Eifelgau only covered the smaller region roughly around the sources of the rivers Ahr, Kyll, Urft and Erft. Its name was more recently transferred to the entire region.

The Eifel belongs to that part of the Rhenish Massif whose rolling plateau is categorised as peneplain highland (Rumpfhochland), which was formed by the erosion of the ancient mountains of the Variscan mountain building phase and subsequent further uplifting. Individual mountain chains, up to 700 m, such as the Schneifel and High Fens, run through the western part of the plateau. In the eastern part, in the High Eifel and Volcanic Eifel, individual cinder cones and basalt kuppen, like the Hohe Acht and the Ernstberg, emerged as a result of volcanicity in the Tertiary and Quaternary periods and rise above the undulating countryside. The rivers draining into the Moselle, Rhine and Meuse, such as the Our, Kyll, Ahr, Brohlbach and Rur, have cut deep into the edge of the Eifel and formed larger valleys. The Eifel covers an area of 5,300 km2 and is geographically divided into the North and South Eifel. It is further divided into several natural regional landscapes, some with further subdivisions.

Since 2004, part of the North Eifel has been designated as the Eifel National Park. There are also four nature parks in the Eifel (from north to south): Rhineland, High Fens Eifel, Volcanic Eifel, and South Eifel, although the first extends only partly into the northern foothills of the Eifel.

Due to its moist and mild Atlantic climate, the Eifel is bisected by numerous streams and small rivers. Impoundment of these streams, especially in the North Eifel has led to the creation of very large reservoir, such as the Rursee, which is the second largest in Germany by volume, and the Urftsee. A feature of the Eifel are its natural lakes of volcanic origin. The largest, the Laacher See, is a collapsed, water filled caldera, whilst the many maars are water filled volcanic eruption bowls. The largest maar lake is the Pulvermaar. The Meerfelder Maar has an even bigger basin, but three quarters of it has silted up.

Despite the interesting geology of the Eifel region, only three comprehensive geological accounts have been produced. and folded and overthrust in the Variscan orogeny. Only on the northern edge of the Eifel, in the High Fens and its environs, do older rocks from the Cambrian and Ordovician outcrop. Rocks of the Carboniferous do not occur in the Eifel itself, but lie along its northern boundary in the region of Aachen. The Devonian rocks were deposited in an oceanic basin, in which erosion debris was washed in from the north from the great north continent of Euramerica (Laurussia or the Old Red Continent) which was formed by Caledonian mountain building during the Silurian. From the end of the Lower Carboniferous the sea basin was caught up in the Variscan mountain building process, pushed together and uplifted, and thus formed part of the Variscan mountain system that, in the Upper Carboniferous and early Permian, covered large areas of Europe. The Eifel geological structures like main folds and overthrusts can be traced in a SW NE direction far beyond the Rhine valley.

Since that folding, the Eifel has largely remained part of the mainland. During the Permian, after the end of the uplifting, the Variscan mountains were heavily eroded, leaving only a relatively flat, truncated upland. For a short time, and only partially, this was later flooded by the sea. Depositions from the Triassic and Jurassic periods have survived in the so called Eifel North South Zone. This is a region of subsidence, which runs from the Trier Bay in the south to the Lower Rhine Bay in the north. Through this zone existed at one time a sea link between north and south Central Europe. The remains of the sediments laid down at this time have survived to a greater extent in the Maubach Mechernich Triassic Triangle in the north and in the Oberbettingen Triassic Graben in the area around Hillesheim and Oberbettingen. In the Upper Cretaceous and during the Tertiary, the Eifel was inundated mainly from the north. Remains of Cretaceous rocks were discovered on the High Fens. Scattered patches of Oligocene deposits can be found there and in the Western Eifel. From the Pliocene onwards, the Rhenish Massif, including the Eifel, experienced an uplift. This led to the streams and rivers cutting into the gently rolling landscape resulting in the present appearance of the low mountain range with its flat plateaus and deeply incised valleys. Due to numerous recent research projects, climate changes since the last ice age can be traced in detail in the Eifel region.

Volcanic activity in the Eifel began 50 millions of years ago and continues into the geological present. It created numerous volcanic structures, lava flows and extensive layers of volcanic ejecta made of tuff and pumice, which have formed the basis of a significant mining activity for the extraction of building materials since Roman times. Some of the hills are volcanic vents. The peculiar circle shaped lakes (maars) of the volcanic regions formed in volcanic craters. The first volcanic eruptions took place in the early Tertiary centred in the High Eifel and even before the volcanic activity of the Siebengebirge and Westerwald. Volcanism in the High Eifel came to an end about 15 to 20 million years ago, at the same time as that of the Siebengebirge. Volcanism in the western and eastern Eifel is, in contrast to that of the High Eifel, much more recent than that of the Siebengebirge and Westerwald. It began in the West Eifel region of Daun, Hillesheim and Gerolstein about 700,000 years ago and created a chain of ash volcanoes, cinder cones, maars and craters running in a chain from northwest to southeast. The youngest maars are only slightly older than 11,000  years. In the eastern Eifel, volcanism began about 500,000 years ago in the area of today's Laacher See; it extended to the Neuwied Basin to the south, and crossed the Rhine to the east. The quantity of basalt lavas, pumice tuffs and ash tuffs produced by the volcanoes was far greater here than in the western Eifel. East Eifel volcanism came to an end with a huge eruption, as a result of which the magma chamber emptied and collapsed, creating a caldera. Today's Laacher See formed in the caldera. The ashes from the eruption can be detected today in deposits all over Central Europe and as far as Bornholm as a thin layer. Volcanism is caused by magma, which either rises directly to the Earth's surface from the upper regions of the Earth's mantle or, in the majority of cases, gathers in a magma chamber, several tens of kilometres deep, at the base of the Earth's crust, from which magma rises at irregular intervals and causes volcanic eruptions. Volcanism in the Eifel is thought to be partly caused by the Eifel hotspot, a place where hot material from deep in the mantle rises to the surface, and partly by melt ascent at deep fractures in the Earth's crust. Research has shown that the volcanism is still active; the Eifel region is rising by 1–2 mm per year and there are escaping gases, for example, carbon dioxide (CO2) in the Laacher See.

The Eifel is in the Atlantic climate zone with its relatively high precipitation; winters that are moderately cold and long with periods of snow; and summers that are often humid and cool. The prevailing wind is west/southwest. A relatively dry and milder climate prevails in the wind and rain shadow of the High Eifel. Cold air from Siberia in the higher elevations of the Eifel has less of an impact on weather conditions, as the proximity of the Atlantic Ocean to the Eifel brings milder sea air to the Eifel even in winter. Looking at the long term averages, even the Snow Eifel only has snow cover for nine consecutive days in winter, as there are no longer lasting cold spells. However, there is an average of 70 days of full snow cover because the frequency of snow at higher elevations is relatively high (for comparison: Bitburg 35  days, Maifeld 30  days), but the level of snowfall varies from year to year. Snow heights vary on average between 15 cm and 60 cm. The humid Atlantic climate can cause extreme variations though: on 2 March 1987 there was 227 centimetres of snow in the Eifel on the Weißer Stein. The mean temperature in the coldest month (January) is 1.5 °C at high elevations, +1.5 to 2 °C in the mountain foreland. There is an average of 110 days of frost, with temperatures below 0 °C in the highlands and an average of 30 to 40 'ice days' when temperatures do not rise above 0 °C. The warmest month (July) only has an average temperature of 14 °C in the higher areas. The level of precipitation decreases significantly from west to east as a result of the rain shadow of the highlands. So the Schneifel receives an average of 1,200 mm of precipitation (High Fens: 1,400 mm to 1,500 mm), while in Maifeld the average rainfall is only 600 mm. The bioclimatic conditions in the Eifel are favourable. Heat stress and air humidity are rarely present in summer. The Eifel has a distinctly stimulating climate; the high elevations being considered as highly stimulating. The Eifel is a clean air area with very low air chemical pollution. On hot sunny days, there is sometimes an increased concentration of ground level ozone. Here are a couple of weather station examples for settlements in the Eifel.

At the time of the Roman Empire the whole mountain range between the rivers Rhine, Meuse and Moselle was called Arduenna silva ("high forest"). The oldest record of the name "Eifel" does not occur until the Early Middle Ages. Following the collapse of the West Roman Empire, the Frankish Empire emerged in the territories of present day France and western Germany. This was divided into gaue (Lat. : pagi). One of them, the Eifelgau, covered the source regions of the rivers Erft, Urft, Kyll and Ahr, i. e. predominantly the northern and northwestern foothills of the present Eifel in the eastern half of the Arduenna silva of the Romans. West of the Eifelgau lay the Ardennengau, whose name was derived from Arduenna silva. Following the end of the Frankish Empire the name of the old gaue continued to be used in popular language. Over the centuries an ever larger region was referred to as the Eifel. Today the whole German speaking part of the range between the Rhine, Meuse and Moselle is called the Eifel (including several areas outside of Germany, see the → Belgian Eifel), while the French speaking part in Belgium and France is called the Ardennes.

Müller/Schnetz (1937) believe that an n has dropped out between the diphthong and the syllable, fel. The resulting root form Anfil or Anfali would then mean an "area that is not so level". An would then be a prefix and fali, which is related to the Slavic polje ("field"), means "plain" or "heath". W. Kaspers (1938) deduces from the surviving form in pago aquilinse the root form aku ella, akwella and points to its development into the name "Eifel" in the following sequence: aquila > agfla > aifla > eifla > Eifel. Akuella derives from the pre German and means "land with summits" or "land with peaks". Both propositions, like several others, are highly contentious. The most convincing proposal is that of Heinrich Dittmaier (1961). Dittmaier initially derives it from the Germanic Ai fil. The second component corresponds to Ville, which is the name of a ridge between the Erft, Swist and Rhine today. The variants Vele, Vile and Viele may often be found in place names such as Veler Weg or Veler Pfad. Unlike the modern word Ville the fricative consonant is hard in "Eifel". Responsible for that was probably a sound between ai and fil, which was assimilated by the f, possibly f, k, ch, d, t. Dittmaier believes the missing sound was a k or ch, whereby "Eifel" originally went back to Aik fil. Aik/Aich is also a name for oak (Eiche) and qualifies the root word ville. On the basis that it was covered by oak trees, the Eifel (= Eich Ville) could thus be distinguished from the other Ville, a name still used today, on the Erft. However, the original, historical and even current vegetation of the present day Ville is dominated by oak mixed forest. The meaning of "Ville" is also disputed. Dittmaier gives three possible explanations: "marshy region", "plain, heath" and "heathland", which would all bring geology and vegetation into harmony. Another proposal sees the name as even older and possibly of Celtic origin. Near Cologne, an altar was found, which was dedicated to Matronae Aufaniae Celtic goddesses which were honoured by flowing water. The thesis that the name "Eifel" was derived from this source is not conclusive, but it is persuasive; Eifel would then mean "land of water" or "watery mountains".