Geoscience Reference
In-Depth Information
followed a three- or four-year course in chemistry, mining methods,
mineralogy and mathematics. Werner taught amongst other courses
geognosy - defined as the science or theory of the formation of the
Earth; petrography - the study of rocks; and mineralogy - the study of
minerals, particularly those applied to mining. He was a meticulous
teacher both in the laboratory and in the field and instilled in his
students the value of making observations and recording their findings
either in notebooks or as geological maps and plans.
Over the years Werner examined large tracts of Saxony, its land-
scape and its mines, and in doing so acquired an encyclopaedic knowl-
edge of the geological make-up of the region. It was natural that in his
ordered mind he should start to formulate a classification of the rocks
with which he had now become so familiar. This classification prob-
ably underwent some evolution through time, but it was most
famously expounded and laid down in his short 28-page publi-
cation Kurze Klassifikation und Beschreibung der verschiedenen
Gebu¨rgsarten which he completed in 1785 and published in Prague
the following year. Alexander Ospovat, the foremost student of Wer-
ner in the past fifty years, said of it: '[it] guided geological observations
and formed the basis for rock classifications ... from 1786 until about
1825. It established petrography as an independent branch of the
geological sciences and made the doctrine of geological succession a
cardinal principle of earth history.' Broadly speaking Werner devised a
four-fold classification of the rock succession: (1) Urgebirge: 'primi-
tive' rocks (the oldest and lowermost) such as granite, gneiss, marble,
quartzite and basalt in which fossils were not found; (2) U
¨
bergangsge-
birge: 'transitional' rocks such as clastic sedimentary rocks and lime-
stones with frequent fossils; (3) Flo¨tzgebirge: 'Floetz' rocks which
were well-bedded limestones, shales, coals, clays and sandstones
with frequent fossils; and finally (4) Aufgeschwemmte Gebirge: the
overlying (and youngest) 'alluvial' rocks which comprised unconsoli-
dated gravels, sands, soils and peat. In these he recognised many
reworked fossils from the underlying Floetz. He also suggested that
volcanic rocks (such as tuff, lava, ash and pumice) could occur at any
