Early in his career, Walther set himself the aimof ‘modernizing’ Lyell’s uniformitarianism.. At the time when he wrote his principal works, palaeontology, stratig-raphy, and tectonics do
Trang 1Early in his career, Walther set himself the aim
of ‘modernizing’ Lyell’s uniformitarianism Thus he
undertook journeys to study as many geological
con-ditions and environments as possible, but he focused
on two fields in particular: shallow marine
environ-ments (including reefs) and deserts At the time when
he wrote his principal works, palaeontology,
stratig-raphy, and tectonics dominated geology in the
univer-sities, but Walther did not focus on these fields
Sedimentary rocks were chiefly studied because of
their fossil content, useful for stratigraphy, and not
because they illustrated former environments Strongly
influenced by Haeckel, the German apostle of
Darwin-ism, Walther applied his ideas to geology by looking at
the mode of formation of sediments, and the processes
that formed rocks, not just their characteristics His
credo was: ‘‘Aus dem Sein erkla¨ren wir das Werden’’
(From the present state [of a rock] we explain its
origin) But he was well aware that some past processes
do not occur today Though physical laws remain
the same, geological conditions vary and may even
be unique
With this dynamic approach, Walther was able
to integrate climatological, sedimentological,
palae-ontological, and other aspects into Amanz Gressly’s
‘facies’ concept (1838), which was the basis for
Walther’s comprehensive consideration of facies His
view of the succession of palaeoenvironments was
expressed in the ‘Law of Facies’, which was
subse-quently named after him (even though it had already
been found by Gressly): ‘‘Es ist ein Grundsatz von
weittragender Bedeutung, dass primaer sich nur
solche Facies und Faciesbezirke geologisch
u¨berla-gern ko¨nnen, die in der Gegenwart nebeneinander
zu beobachten sind’’ (‘‘It is a principle of far-reaching
importance that only the facies or facies areas that are
at present adjacent to one another can be geologically
superimposed upon one another’’) (Walther [1894],
p 979; see also Middleton [1972]) In other words,
the relative horizontal distribution of sediments with
their organic content will be transformed into a
verti-cal distribution, having a chronologiverti-cal order Gressly
found the rule during his extended fieldwork for his
admirable monograph on the Swiss Jurassic near the
town of Solothurn, where he carefully studied the
facies changes Fifty years later, Walther discovered
Gressly’s study of 1838 anew, when he was working
for his volume on lithogenesis He explained and
discussed this idea in detail in the first of three
chap-ters on facies in his most interesting third volume
(Lithogenesis of the Present) of his fundamental
work, Einleitung in die Geologie als historische
Wis-senschaft (1894) This discussion of the ‘law’ was only
a minor part of the total corpus of his work, but it is
on this that his present reputation chiefly rests
Walther stressed the importance of organisms in geological processes and vice versa: biogeology The dependence of biocenoses (groups of organisms living together, forming natural ecological units) on their substrates means that lithology should have priority over palaeontology He mentioned, for example, that the empty shells of index fossils can be transported over long distances and may, therefore, give false stratigraphic results With his zoological background
of comparative anatomy Walther thus advocated
‘comparative lithology’ This concept improved stra-tigraphy substantially and Amadeus W Grabau (1870–1946) paid tribute to it by dedicating his classic Principles of Stratigraphy (1913) to Walther The first of the other two volumes of Walther’s Introduction to Geology as Historical Science (see above), Bionomie des Meeres, was a treatise on marine biogeology that dealt with the interactions between the sea floor, fauna, and flora; beyond that it also had chapters on oceanography (He had previously pub-lished a popular booklet on general oceanography in 1893.) The second volume was mostly a collection of faunal lists
All Walther’s pioneering work was undertaken in his years in Jena One of his later publications was the voluminous Allgemeine Pala¨ontologie (General Palaeontology) (1927) He wanted to give a summary
of all the topics he had thought and taught about, and this was a lot The book contained a wealth of varied ideas, though regrettably a number of them were already outdated by the time the book appeared With its 809 pages, it presents difficult, yet still inspir-ing readinspir-ing For Walther, theories were much more important than details
Special Contributions
Shallow Marine
Walther’s final study on the sediments of Dove Bank (Taubenbank, 1910), a shoal in the Gulf of Naples, was a classic He compared his first maps of 1884 with the latest findings of 1910 to evaluate the changes caused by volcanic activity (Vesuvius pro-duced a great ash-fall in 1906) and the unusual storms
of the intervening years (an early look at event stra-tigraphy!) His former studies of the rock-forming calcareous algae (1885) enabled him to compare his old and new results He showed that coralline algae spread rapidly, consolidating sediments within
25 years
Perhaps even more interesting was Walther’s appli-cation of biological experiments to explain bioturba-tion, which he stated could occur down to 15 cm He also measured the digging velocity of mussels Using
FAMOUS GEOLOGISTS/Walther 243