The study area of the distribution of the populations of the Stag Beetle Lucanus cervus in the sur-roundings of Heidelberg and Mannheim is located in the middle part of the Upper Rhine valley as well as in the westwards and eastwards adjacent highlands of the Palatinate Forest, the Odenwald and the Kraichgau in the southwestern part of Germany. The outline of geography and geology of the study area focusses on Quaternary fluvial sand plain with vegetated aeolian dunes of the Upper Rhine valley; Mesozoic sediments in the highlands of Palatinate Forest, Vosges, Odenwald, Kraich-gau and Black Forest; Variscan basement in the central parts of Odenwald, Black Forest and Vos-ges; Quaternary aeolian loess cover in Upper Rhine valley and adjacent highlands, Tertiary mafic volcanoes in Upper Rhine valley and adjacent highlands, and elevation above sea level.
3.1 Quaternary fluvial sand plain with vegetated aeolian dunes of the Upper Rhine valley
The band-like plain of the Upper Rhine valley extends as an elongated north-south-trending depres-sion zone from Mainz westsouthwest of Frankfurt am Main in the north via Darmstadt, Worms, Mannheim/Ludwigshafen, Heidelberg, Karlsruhe, Rastatt, Strasbourg, Offenburg, Lahr, Freiburg
and Neuenburg to Basel in the south. The Upper Rhine valley is geologically a graben and geomor-phologically a plain of abt. 35 – 40 km width which is surrounded by the highlands of the Palatinate Forest and the Vosges in the west as well as the Odenwald, the Kraichgau and the Black Forest in the east. The marginal faults of the Upper Rhine graben are nowadays still active in some extension which is also reflected by the occasional occurrence of isolated and restricted little earthquakes from time to time in different parts of the area that are too weak to cause visible damage to build-ings except of sometimes a few thin cracks of limited length in the walls of some houses. Some of these little natural earthquakes in the surroundings of the marginal faults of the Upper Rhine graben have happened in Heidelberg and vicinity at the eastern margin of the Upper Rhine graben on 26.02.1969 (HEIDELBERGER TAGEBLATT 1969), 03.09.1978 (RHEIN-NECKAR-ZEITUNG 1978) and 26.03.2005 (RHEIN-NECKAR-ZEITUNG 2005), whereas another little earthquake that has occurred in Landau southwest of Heidelberg at the western margin of the Upper Rhine graben on 15.08.2009 has probably been stimulated artificially (RHEIN-NECKAR-ZEITUNG 2009d). I have experienced the little earthquake on 03.09.1978 during my time as a student at the university of Heidelberg when I have felt a weak shaking of the ground with a slight wobbling of cupboards and lamps in my rooms in Walldorf in the early morning of that day.
The plain of the Upper Rhine valley is covered mainly by Quaternary fluvial sand sheets and strings of the river Rhine and its tributaries (among others the Neckar around Heidelberg and Mannheim), with in some regions groups of vegetated Quaternary aeolian sand dunes sitting as small patches on the fluvial sand flat (MADER 1995a) and reaching a height of abt. 10 – 20 m (such as for example around and between Sandhausen and Walldorf south of Heidelberg as well as around Schwetzingen and Oftersheim westsouthwest of Heidelberg).
3.2 Mesozoic sediments in the highlands of Palatinate Forest, Vosges, Odenwald, Kraichgau and Black Forest
The highlands of the Palatinate Forest, the Vosges, the Odenwald and the Black Forest are mainly built up of continuous sheets of red fluvial and aeolian sandstones of the Buntsandstein (Lower Triassic; MADER 1985a, 1985b, 1992a, 1992b, 1999) which cover either limited fans, lenses and wedges of red fluvial sandstones, lacustrine mudstones and acid or mafic volcanites of the Rotlie-gendes (Lower Permian; MADER 1992a, 1999) or rest with erosional and/or angular unconformity immediately on the granite and gneiss of the eroded Variscan basement that has formed the pre-Per-mian or pre-Triassic surface of the landscape with a pronounced relief including elevations and de-pressions. The highland of the Kraichgau is predominantly composed of continuous sheets of grey marine limestones of the Muschelkalk (Middle Triassic) and yellow, green, grey and red fluvial sandstones and lacustrine mudstones with intercalations of grey lacustrine limestones of the Keuper (Upper Triassic; MADER 1990, 1992a, 1995b, 1997). The fluvial sandstones and lacustrine mudsto-nes of the Upper Buntsandstein and the Middle Keuper contain numerous typical blue-violet and red-violet horizons which represent calcrete palaeosols that include frequently fossil root levels, and include also various breccia layers which constitute deposits of reworked fragments of calcareous concretions and root tubes from blue-violet and red-violet calcrete palaeosols (MADER 1990, 1992a, 1997). The geological boundary between Odenwald and Kraichgau as well as between Black Forest and Kraichgau is represented by the boundary between the red continental Buntsandstein and the grey marine Muschelkalk at the current surface of the landscape.
In some regions of the plain of the Upper Rhine valley and its margins, also black marine mudsto-nes of the Liassic (Lower Jurassic) or yellow, green and grey marine sandstomudsto-nes and limestomudsto-nes of Eocene, Oligocene and Miocene (Tertiary) participate in limited troughs and synclines in the con-struction of the landscape.
The red, yellow, green and grey terrestrial sandstones of Buntsandstein and Keuper have formerly been used as building stones for castles, fortifications, churches, cathedrals, monasteries, palaces, town halls, city walls, city gates, towers, bridges, monuments and numerous houses in extensive areal distribution. In the highland of the Palatinate Forest, the alternation of harder fluvial sandsto-nes and weaker aeolian sandstosandsto-nes in the stratigraphical record of the Buntsandstein and the tectoni-cal framework of a slight inclination of the geologitectoni-cal formations has allowed the development of spectacular rock monuments on the tops and flanks of many hills in both the open and forested ter-raced or stepped landscape, with the shapes of the denudation remnants of the Buntsandstein piles that have been created by the continuous erosion by water and wind encompassing among others tables, mushrooms, umbrellas, boots, pillars, towers, stairs, bridges, gates and arches (MADER 1995a, 1992a). Pronounced terraces and steps in the landscape of Palatinate Forest, Odenwald and Black Forest which are created by strongly-cemented layers of the Buntsandstein that are resistant against weathering are repeatedly the places of fascinating and attractive waterfalls.
3.3 Variscan basement in the central parts of Odenwald, Black Forest and Vosges
In the central parts of Odenwald, Black Forest and Vosges, the granite and gneiss of the eroded Va-riscan basement is also immediately exposed at the present surface of the landscape without a cover of Mesozoic sediments or Palaeozoic deposits or volcanites. In most parts of the highlands, how-ever, the granite and gneiss of the eroded Variscan basement that has formed the pre-Permian or pre-Triassic surface of the landscape with a pronounced relief including elevations and depressions is covered by Mesozoic sediments of the Buntsandstein (Lower Triassic) or Palaeozoic deposits or volcanites of the Rotliegendes (Lower Permian) with erosional and/or angular unconformity (MADER 1985a, 1985b, 1992a, 1992b, 1999).
3.4 Quaternary aeolian loess cover in Upper Rhine valley and adjacent highlands
Both the plain of the Upper Rhine valley and the adjacent highlands are in parts covered by blankets and wedges of Quaternary aeolian loess (MADER 1999, 2000) which reaches up to several m thick-ness and is at many places in the landscape exposed in the typical hollow ways, ravines or gorges with quite stable walls consisting of loess and being stabilized by trees, bushes and grasses growing on the loess and rooting in the loess, by calcareous concretions that are dispersed or concentrated to layers within the loess, by loamy recent and fossil soils having developed on the loess or being buried within the loess, and by assemblages of calcareous tubes in ancient root horizons within the palaeosols in the pile of the loess. The loess is one of the best substrates for the widespread viticul-ture of red, blue, green and white grapes from which excellent and world-famous red and white wines and champagnes are produced, and is also one of the preferred substrates for nesting of va-rious bees and wasps that favour insolated slopes of hollow ways and other exposed profiles of the loess for nidification.
3.5 Tertiary mafic volcanoes in Upper Rhine valley and adjacent highlands
The highlands surrounding the plain of the Upper Rhine valley are in places perforated by the ero-ded remnants of Tertiary mafic volcanoes (MADER 1985a, 1999), with the geomorphologically most accentuated and the geologically most outstanding member of the assemblage of the denudated ruins of Tertiary mafic volcanoes being the Katzenbuckel east of Eberbach eastnortheast of Heidel-berg which reaches 626 m above sea level at its top and is the highest elevation in the Odenwald (MADER 2009a), and thus represents a significant landmark that can be seen from long distances.
The Katzenbuckel is geologically highlighted by its unique assemblage of alcaline basaltic volcanic and subvolcanic rocks as well as by inclusions of xenoliths of fossiliferous marine mudstones of the Dogger (Middle Jurassic) in the breccia filling parts of the volcanic pipe that document the removal of cover strata of abt. 600 m thickness by erosion since the eruption of the Tertiary Katzenbuckel volcano (FRENZEL 1975). Another famous downgraded relict of Tertiary mafic volcanoes in the high-lands adjacent to the plain of the Upper Rhine valley is the Steinsberg south of Sinsheim southeast of Heidelberg that reaches 333 m above sea level at its top and is known as the compass of the Kraichgau, and at the northern margin of the Odenwald, the most pronounced eroded remnant of Tertiary mafic volcanoes is the Otzberg southsouthwest of Groß-Umstadt eastsoutheast of Darm-stadt which reaches 368 m above sea level at its top and permits the orientation over large areas in the broad plain of the Main valley between Frankfurt am Main and Aschaffenburg.
Within the southern part of the Upper Rhine valley, the outstanding Tertiary volcanic complex of the Kaiserstuhl northwest of Freiburg resides like a crown of mountains on the fluvial sand plain and is similarly as the Katzenbuckel in the Odenwald world-famous for its exceptional petrographi-cal assemblage of extraordinary volcanic and subvolcanic rocks, with several types of special volca-nic and subvolcavolca-nic rocks of Kaiserstuhl and Katzenbuckel being unique in the world and occurring nowhere else in such a composition as at Kaiserstuhl and Katzenbuckel.
3.6 Elevation above sea level
The elevation above sea level within the study area is abt. 100 m in the plain of the Upper Rhine valley and extends up to abt. 600 m in the highlands of Odenwald, Palatinate Forest and Kraichgau surrounding the middle part of the Upper Rhine valley, whereas outside of the study area, the highest mountains in Black Forest and Vosges adjacent to the southern part of the Upper Rhine val-ley reach up to abt. 1,500 m.