Cópia Física
- "His main theoretical contributions were his championing of the actualistic method for the study of fossils and sedimentary rocks and his founding of the science of comparative lithology. Comparative lithology was seen by Walther as the analogue for sedimentary rocks of comparative anatomy for fossils. It has been neglected in the West until the recent revival of the concept of facies models." (979)
Original Translation of Walther's Law of the Correlation of Facies: "The various deposits of the same facies areas and similarly the sum of the rocks of different facies areas are formed beside each other in space, though in cross-section we see them lying on top of each other. As with biotopes, it is a basic statement of far-reaching significance that only those facies and facies areas can be superimposed primarily which can be observed beside each other at the present time." (979)
Walther's Law, prior to the reemergence of the 60s and 70s has been either neglected or misstated (cf p. 982-983 for the 3 crucial aspects that illuminate the Law)
- "...the law itself must be understood in the larger theoretical context in which it was developed by Walther. Seen in this context, it was an outstanding theoretical advance for its time (1894)." (980)
Walther prefered the term "Ontological Method", instead of Actualism or Uniformitarianism, as a complement to the Paleontological Method
p. 982: Summary of Walher's thoughts on the matter, chap.27 of "Einleitung in die Geologie als historische Wissenschaft" (1893):
From the incompleteness of the rock record to the inferrence of related rocks by association (much like comparative anatomy and the correlation of organs), the same facies area (Faziesbezirke = Depositional Environment nowadays) will generate related (associated) facies, which can be recognized by its primary characteristics (the ones imprinted on the rocks by the features of the depositional environment, not through diagenesis or metamorphism.
The missing facies and rocks can be inferred (we recreate them) through our knowledge of PRESENT environments and their associations: "We must search in the surroundings of the fossil deposit and complete the missing facies according to the laws of correlation, just as the paleontologist completes his fragmentary remains by following the laws of the correlation of organs" (982) [The promise of prediction and causality]
p. 982: Commentary on Walther's Law and its theoretical underpinnings:
3 crucial aspects ("emphasis on modern enviroments, the causal structure of the law, and its setting within the science of comparative lithology" (984))
- Actualism (the Ontological Method): everything stems from it, the basis for inferrence and association is what can be observed in the present time: modern environments ==> facies ==> ancient sequences;
- Only facies that are genetically related CAN PRIMARILY BECOME A VERTICAL SEQUENCE; not necessarily every facies will be there, but certain relations are permited and others are not;
- The Law is intimately connected to Walther's Comparative Lithology (from primary characteristics to inference of environment); away from mere cataloging to causality and inference
Walther believed that his Law was tentative, or general, and should be substituted by laws for every depositional enviroment (modern "facies models"). The great aim of lithology (as understood by Walther and the russians cited (e.g. Golovkinskii, Inostranzev...)) is not description but interpret the facies and explain lithogenesis. Modern facies models: finite numbers of recurrent patterns of sedimentation, and knowledge derived from well-described modern sedimentary environments.
NOTAS
- "It was Walther (1893-1894)...was to adopt [the term Diagenesis] it in a masterful way by opening a new chapter in sedimentology" D. de Segonzac p.157.
- In a way, the close connection between russian scholars and the research developed by knows nazi/collaborators (e.g. Weigelt, Richter) in post-WW2 days.
- To the classical trilogy of erosion, tranportation and sedimentation, Walther brings new elements. He splits the geochemical cycle into seven stages, thus pointing to the 'stadial analysis' which the Russians are to push so far: (1) "Verwitterung"; (2) "Ablation"; (3) "Transportation"; (4) "Corrasion"; (5) "Auflagerung"; (6) "Diagenesis"; (7) "Metamorphosis". D. de Segonzac p.157.
- "Cyclic stratigraphic body" =? "cyclothem (Duff and Walton).
- There is, therefore, a russian school that has been neglected in traditional whig history of geosciences. The existence of this great tradition makes Efremov no fish out of the water.
