Home , ältere Neujahrsblätter, Neujahrsblatt für Kinder und Jugendliche     Aus der Frühzeit der alpinen Geologie:   Johann Gottfried Ebels Versuch einer Synthese  (1808)   von Sibylle Franks, Rudolf Trümpy und Josef Auf der Maur   mit 1 Farbtafel, 12 Figuren und 1 Tabelle

Summary Johann Gottfried Ebel (1764-1830) was born in Prussian Silesia. He obtained his M.D. at Frankfurt (Oder) but never had a regular practice. Like many of his enlightened contemporaries, he was suspected of sympathies for the French Revolution. He lived in Frankfurt (Main), Paris and Switzerland, where he was awarded a citizenship in 1801 and where he had close relations with members of the reform movement. His later years were spent in Zurich. Ebel became especially known as the author of travel handbooks and of studies of Swiss customs and institutions. In 1808, he published the two volumes of his «Bau der Erde in dem Alpengebirge», the very first, and for a long time the only, attempt at a geological synthesis of the Alps and their foreland. They contain a map, cross-sections and panoramas. Ebel's theoretical base was derived from the teachings of Abraham Gottlob Werner and Peter Simon Pallas. His data were derived from his own observations and those of his numerous correspondents. Among his published sources, the writings of Horace-Benedict de Saussure and of Hans Conrad Escher were the most important ones. His «system» may be described as follows: The core of the Alps is formed by Primitive Rocks, «as old as the Earth itself». They comprise not only granites, gneisses, micaschists and other basement and metamorphic rocks, but also bands of limestone, slate and the like, which had already been recognized by de Saussure as remnants of«Secondary» formations. All the strata are steeply inclined, invariably striking WSW - ENE and often dipping toward the S. For Ebel, as for a true Wernerian, these rocks were precipitated out of the broth of a «primordial sea», in their present, steep-standing position. His system is «ultra-autochthonist». The Calcareous Alps, to the N and to the S, were deposited on both sides of the Primordial Chain. Apart from limestones, they also comprise gypsum, slates and graywackes. The steep inclinations and other - for Ebel, only local - disturbances of bedding are due to the irregular relief of the underlying primordial rocks. Among the [Tertiary] rocks of the Swiss Plateau, Ebel distinguishes an older formation of inclined conglomerates and sandstones, along the border of the Alps, and a younger one of flat-lying sandstones and marls, capped in their turn by (younger) conglomerates. The Alps are a ruin; originally, they were many thousands of feet higher. Their destruction, and the carving of the valleys, are due to a minor extent to processes which are observed today, but mainly to repeated, catastrophic marine floods from the SE. The first two are responsible for the older and younger conglomerates; the last and greatest of them transported the [erratic] boulders to the foot of the Jura hills.

Ebel concludes with general rules for the origin of mountain belts, inspired by the romantic German «Naturphilosophie» of his times. Some of his speculations are rather far-fetched, others show astonishing insights. More than a century before Milankovic, he realized that the periodic variations of the Earth's astronomical parameters must have had a decisive impact on the distribution of climates. In order to accommodate the «facts» (observations) to his theory, Ebel is of course obliged to stretch the evidence, in some cases quite outrageously so. His volumes have been severely criticized by contemporaries, especially by Escher and largely ignored by modern geologists and historians. The most obvious weakness of Ebel's system is his failure to understand the importance of tectonic deformations, unlike de Saussure, Escher and Leopold von Buch. He does not seem to have been aware of James Hutton's work. Nevertheless, this early, perhaps premature venture to formulate a genetic theory of the Alps conveys an interesting picture of early 19th century geognosy Our paper is mainly based on published documents, except for chapters 4.2 and 4.3, which show Ebel as a controversialist shortly after the publication of his volumes and as a mentor of younger scientists toward the end of his life, and for which manuscripts in various archives have been consulted. Quotations are italics, present interpretation of ancient terms in [square brackets].

Ausgegeben am 31. Dezember 2000; ISSN 0379-1327
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