Neptunism

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The "founder" of Neptunism, AG Werner

The Neptunism (or Diluvianismus) is a warped geological view, according to which all rocks sedimentary rocks , that is, are inherently water of the oceans have accumulated. Neptunism is in contrast to the doctrine of Plutonism (also: volcanism ).

Origins and early representatives

Some authors (e.g. the geologist Arnold von Lasaulx ) regard the natural philosophy of the Greek philosopher Thales von Milet as an early forerunner of the theory , according to which all things originated from water, even if this doctrine of cosmogony rather than petrography must be added. Also Xenophanes , the fossil record discovered on mountains, can be precursors of Neptunism.

The establishment of geology as a science in the 18th century was accompanied by the formulation of Neptunist theses by numerous early proponents, so that it was difficult to find a first “originator”. For many of these early Neptunists, the observation that basalt rock is often found in separate, columnar forms, which are interpreted as crystals, plays an important role . The associated crystallization is then naturally thought of as a process that took place from an aqueous medium. A corresponding thesis can be found, for example, in the German geologist Johann Ernst Immanuel Walch in his “ Steinreich ” from 1764 (quoted from). Other representatives of Neptunism from the early 18th century include Axel Frederic Cronstedt , Johann Friedrich Wilhelm von Charpentier , Johan Gottschalk Wallerius and Torbern Olof Bergman .

Already in this early period the first opponents of the theory appeared among geologists, such as the French scientists Nicolas Desmarest and Jean-Étienne Guettard .

Abraham Gottlob Werner

The geologist Abraham Gottlob Werner (1749–1817) is often named as the “founder” of Neptunism , but his role is better described with the following quote:

“If his name is intimately connected with this controversial issue, then the reason for it lay in the surprising turn which was brought about by his intervention; he did not cause the quarrel, he found it and only brought about a long postponed decision by taking on those who were almost underlain with the most effective weapons. "

The forcefulness of Werner's arguments becomes understandable if one takes into account that he was one of the great scientific authorities of his time, who is still rightly named as one of the founders of modern geology, and that his considerations on the genesis of basalt, which are essential were based on investigations at the Scheibenberg in Saxony in the years 1787/88, were integrated into an overarching theoretical structure, which was based entirely on careful observations and would by no means have been consistently flawed.

Werner's theory

The theory is based on a division of the rock groups into four main types. The classification includes the following basic units:

Smooth transitions from one rock group to the other are possible.

The term "primeval" means that these rocks represent the earliest and most primitive formations on the earth's body. From a primordial ocean with steadily falling sea levels, these primeval mountains crystallize out first through chemical precipitations. Since then, they have been exposed to wind and surface water erosion , reducing their vertical thickness. These primeval mountains were formed at a time when there was still no life on earth, so these rock units never contain fossils . The "other 3 main species" are deposited one after the other in the foreland and can partly consist almost entirely of the reclaimed material from the first unit. They are thus chronologically behind the "primeval" ones. That is, they are geologically younger. Due to the ongoing regression of the sea, these rocks are now exposed on the mainland and are themselves subject to erosion . Evaporation processes are seen as the main trigger and driver of this continual decline in sea level. An unsolved problem of Neptunism was the emergence of volcanic mountain species. Werner suspected that volcanism was caused by underground coal fires . However, only local significance was assigned to these phenomena.

Contemporary opponents

This hypothesis was pushed back at the beginning of the 19th century, especially by Alexander von Humboldt . During his South American expedition, Humboldt had collected numerous geognostic data that contradicted Neptunism. However, he stuck to the Neptunist interpretation of his teacher Werner until the end of his journey. It was not until 1826 that Humboldt publicly admitted to the competing theory of plutonism in a lecture entitled “On the structure and mode of action of volcanoes in the various stretches of the earth” . Humboldt was able to prove, for example, that porphyry and basalt are of volcanic origin and thus volcanic rock .

The research of the geologist Leopold von Buch - especially on Vesuvius and in the Auvergne - made a major contribution to shaking Neptunist ideas. In the Auvergne, for example, Buch was able to establish that the volcanic rocks were directly deposited on granite there and thus there were no coal-bearing layers in the subsoil that could have provided the material for seam fires (and thus the necessary heat source for the volcanic phenomena according to Neptunist thinking) .

Reception outside of the natural sciences

The German poets Novalis and Johann Wolfgang von Goethe were also among the followers of Neptunism. However, Goethe later changed his followers, particularly under the impression of Alexander von Humboldt's reports on volcanoes, and recognized his progressive investigations.

For the 18th century, the two opposing doctrines were metaphors for the revolution (Plutonism) and the conservative idea (Neptunism).

Neo-septunism

Around the middle of the 19th century - especially through the work of Johann Nepomuk von Fuchs and Karl Gustav Bischof - there was a revival of Neptunist theses.

As a chemist, Fuchs had dealt with the so-called water glass and in doing so apparently solved an old problem of Neptunism: once all rocks have separated out of water, this process should in principle also be reversible; however, most of the minerals and rocks present in the earth's crust (especially the silicate ones) are only sparingly soluble. So either there must have been a lot more water once in the history of the earth (but where is it now?), Or the silicates must once have been much more soluble (but why?). The water glasses seemed to solve the problem - they are alkali metal silicates, which are relatively easily soluble in water and where silica can separate out of the aqueous solutions, which is initially an amorphous, soft gel, but then changes to the crystalline state can. These processes are also irreversible, so they cannot be resolved again. Fuchs now postulated that these transitions could also have occurred in nature and would have contributed to the formation of the known rocks. A formation of the silicate rocks from the melt therefore no longer seemed absolutely necessary.

A little later, the chemist Karl Gustav Bischof , who worked in Bonn, argued in a similar way in his textbook on physical and chemical geology : He initially emphasized quite correctly that when setting up geological theories about rock formation, care should be taken that these explanations were in accordance with the known laws of chemistry and physics. Subsequently, however, he particularly emphasized the importance of water in geological transformation processes. In particular, he explained that, according to his experiments , all rock-forming minerals (with the exception of augite and leucite ) could be formed in an aqueous environment even under normal pressure and temperature conditions, ultimately leading to the conclusion that all known rocks (with the exception of the volcanic lavas) were formed under the influence of water. (In the supplement volume from 1871 published by Ferdinand Zirkel after his death , however, he recognizes the magmatic formation of basalt with the words: "Where there is such a similarity between rocks in chemical, mineralogical and physical properties as between lavas and basalts, there it is justified to infer the same origin. " )

In Germany, neo-septunism found further supporters, particularly in the academic environment of Fuchs in Munich; here the paleontologist Johann Andreas Wagner , the professor of geognosy Karl Emil von Schafhäutl and the geologist Gustav Georg Winkler can be mentioned. The latter had toured the island of Iceland in 1858 and in the publication of the scientific results of this trip declared almost all rocks and formations there - especially the plateau basalts in the West Fjords - to be sedimentary. In doing so, he explicitly referred to Bischof's experiments on rock formation and consciously set himself in contradiction to practically all geologists who had explored Iceland up to that point (such as Robert Wilhelm Bunsen , Otto Ludwig Krug von Nidda and Wolfgang Sartorius von Waltershausen ). Outside Germany, the theory was taken up by numerous scientists, especially in Russia.

One opponent of neo-septunism was the geologist Hermann Vogelsang , who in his Philosophy of Geology accused Bishop in particular of not having sufficiently taken into account geological reality when setting up his theories, but only based his theories on laboratory experiments. He also stated that a universalistic theory of rock formation such as neo-septunism could no longer adequately take into account the geological knowledge gained since the first Neptunism dispute. Here he emphasized the role of metamorphosis as an alternative way of rock formation.

Neoneptunism, however, did not achieve the importance in geology that Neptunism had in the 18th century. In addition to the discomfort with the universalistic approach, it may also have played a role here that for some neo-septunists recognizable ideological motifs were decisive: The emergence of all rocks from the water was part of the biblical account of creation ( “And God said: Let the water collect under the Heaven in a special place that you can see the dry, and it happened that way. " Genesis 1,9) not in contradiction. Thus, the discussion about the theory can also be seen as an “extension” of the materialism dispute in the geosciences, whereby the proponents were sometimes more concerned with the defense of belief than with scientific knowledge.

In the 1860s, neo-septunism came under increasing pressure with the introduction of thin sections as a new analysis method for rocks. Both the German pioneer of thin section research Ferdinand Zirkel and Hermann Vogelsang used the method to draw conclusions about their formation from the microscopic features that were now recognizable. The comparison between natural rocks and artificial products such as slag was particularly fruitful, since the latter undisputedly arose from the molten state. These findings increasingly supported the assumption that the igneous rocks had also crystallized from the melt. On the other hand, the readiness of geologists also grew to recognize the fundamental importance of water in geological transformation processes (for example, in this case, Circle's speech from 1870), which made the scientific debate less sharp.

See also

literature

  • Abraham Gottlieb Werner: Short classification and description of the different mountain types. Walther, 28 p., Dresden 1787
  • Gerd-Rainer Riedel, Jochen Klauß, Horst Feiler: The Neptunist Dispute. Goethe's search for knowledge in Bohemia. Schibri-Verlag, 2009, ISBN 978-3-86863-039-8
  • Karl Gustav Bischof, textbook of chemical and physical geology (Bonn 1847–54, 2 vol .; 2nd edition 1863–66, 3 vol .; supplement 1871)
  • Arnold von Lasaulx, The dispute over the origin of basalt. Lüderitzsche Verlagbuchhandlung, Berlin, 1869.

Web links

Wiktionary: Neptunism  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ A. von Lasaulx: The dispute over the origin of the basalt. Lüderitzsche Verlagsbuchhandlung, Berlin, 1869, p. 4
  2. ↑ A. von Lasaulx: The dispute over the origin of the basalt. Lüderitzsche Verlagsbuchhandlung, Berlin, 1869, p. 9
  3. ↑ A. von Lasaulx: The dispute over the origin of the basalt. Lüderitzsche Verlagsbuchhandlung, Berlin, 1869, pp. 9-10
  4. ↑ A. von Lasaulx: The dispute over the origin of the basalt. Lüderitzsche Verlagsbuchhandlung, Berlin, 1869, p. 11
  5. ^ Otfried Wagenbreth: History of Geology in Germany. Enke, Stuttgart, 1999, pp. 28-35
  6. ^ B. Hubmann: Leopold von Buch . In: The great geologists . Marix, Wiesbaden 2009, ISBN 978-3-86539-949-6 , pp. 92-100 .
  7. ↑ A gift to Goethe , University of Jena , with the contact area of ​​metamorphic Hornfels and granite in the Bodetal, Harz
  8. ↑ Mechanism of Vulcanoes, University of Vienna, Wissenschaftstheorie ( Memento of the original from March 4, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.univie.ac.at
  9. ↑ JN Fuchs: About the theories of the earth, the amorphism of solid bodies and the mutual influence of chemistry and mineralogy . Fleischmann, Munich 1844.
  10. ^ W. Fischer: Formation of rocks and deposits in the change of scientific view . Swiss beard, Stuttgart 1961, p. 34 .
  11. ↑ W. v. Gümbel: Bishop, Gustav . In: Allgemeine Deutsche Biographie . 1875, p. [Online version] .
  12. ^ KG Bischof: Textbook of chemical and physical geology . Supplement. Adolph Marcus, Bonn 1871, p. 183 .
  13. ↑ a b H. Hagn: The development of paleontology and geology from the beginnings to the 19th century . In: Communications from the Bavarian State Collection for Paleontology and Historical Geology . tape 35 . Munich 1995, p. 217-237 .
  14. ^ GG Winkler: Iceland. The construction of its mountains and their geological significance. Gummi, Munich 1863, p. 224-302 .
  15. ^ BP Vysockij, MM Romanova: The neoneptunism in Germany and Russia in the second half of the 19th century . In: Journal of Geological Sciences . tape 4 , no. 2 , 1976, p. 367-374 .
  16. ^ H. Vogelsang: Philosophy of Geology and Microscopic Rock Studies . Max Cohen & Son, Bonn 1867, p. 111-122 .
  17. ↑ H. Vogelsang: About the microscopic structure of the slag and about the relationship of the microstructure to the genesis of the crystalline rocks . In: Annalen der Physik (Poggendorf's Annalen) . tape 197 , no. 1 , 1864, p. 101-125 .
  18. ↑ F. Zirkel: The transformation processes in the mineral kingdom; Academic speech given on December 19, 1870 in the auditorium in Leipzig . Lüderitz, Berlin 1871.