Monday, March 14, 2016

The Vosges Massif

Though I have been more interested in the evolution and dispersal of our species than in my own family's genealogy, I decided to investigate the Alsace-Lorraine region along the France-Germany border, an area from which my paternal grandfather's family had immigrated.  Looking at the map, my attention was immediately drawn to the Vosges Massif, west of the Rhine Valley.

Back in the Carboniferous Period, some 300 million years ago (MYA), a mountain range towered above what is now the France-Germany border region.  Throughout the Mesozoic, natural forces decimated these mountains, covering them with erosional and volcanic debris.  Then, late in the Cretaceous (about 70 MYA), the Alps began to crumple skyward; in concert, the roots of the above ancient range bowed upward, forming a geologic anticline, oriented SSW to NNE across the current border of France and Germany.  In the late Eocene and early Oligocene (some 40 MYA), faulting through this uplift, in addition to east-west stretching of the crust, led to the formation of the Upper Rhine graben as the central axis of the anticline dropped relative to its lateral edges; today, the Black Forest of Germany represents the eastern edge of the anticline, the Rhine River flows through the graben's floor and the Vosges Massif is the remnant of the anticline's western edge.

Molded by glaciation, the rounded summits ("ballons") of the Vosges rise above 4600 feet in southern portions of the range (in eastern France) while the northernmost Vosges, in Germany, have eroded to a landscape of low hills.  Tributaries of the Rhine drain the east side of the Vosges Massif, the Moselle River (a large tributary of the Rhine) drains its northern portion and the upper tributaries of the Saone River, which feeds the Rhone, drains the southwest edge of the Vosges Massif.  The range, 75 miles in length, is characterized by grass-covered summits above rich coniferous forest on the mountain flanks; exposures of Precambrian granite dominate the southern Vosges while volcanic and metamorphic Paleozoic and early Mesozoic rocks outcrop in the northern portion of range  Two parks offer access to the Vosges: Parc Naturel Regional des Ballons des Vosges (WSW of Colmar, France) and Parc Naturel Regional des Vosges du Nord (in France, south of Zweibrucken, Germany).