Geoscience Reference
In-Depth Information
approximation for the date of origin of the fi rst “primitive soil.” This estimated date
could be slightly shifted to another value when future research rigorously identifi es
the origin of the fi rst sedimentary rocks. However, soils in the context of today's
meaning have existed only in the most recent eon, the Phanerozoic. More specifi -
cally, they appeared 454 myr (454 million years) ago with the action of living
macro- and microorganisms, e.g., bacteria, and roots of plants.
Because the Earth is constantly changing, the program of its study could focus
either on times of transitions, namely, transition from times with quasi-stable condi-
tions to times with increased rate of change, or on the detection of soil properties in
times of relative “quasi-stability.” The study of paleosols in times of relative stability
is preferable. Within this context paleosols could be studied as a natural body
originating in the past and surviving either as a full soil body or as a vital step link-
ing the past up to recent times. In some instances, only partial signs of the past soil
are detected. Being mixed within recent soil properties, their identifi cation requires
sophisticated instrumentation applicable on the microscale or even on the nanoscale.
When the nineteenth-century geologists found remnants of fossil plants buried
between sedimentary rocks having signs of horizontal fi ne strata, the hypothesis
about old fossil soils was born. However, a conscientious study about them had to
await the elaboration of soil science and soil evolution. Truly buried soils were fi rst
recognized in the nineteenth century between two layers of fair-colored loess each
many meters thick and mutually separated by a thin humus soil horizon and eventu-
ally below it by a reddish-brown horizon. The top many meters thick layer of loess
belonged to the last glacial era named Wisconsin in the USA or Würm in Central
Europe. The bottom loess layer - below the thin buried humus horizon - originated
in glacial era of Illinoian according to US terminology (230-130 kyr BP, kyr = thou-
sand years) or named Riss in Europe. A substantial warming lasting for 15 kyr
occurred between the time of Wisconsin and Illinoian glacials. This interglacial era
is named Sangamonian in the USA and Eemian in Europe. The global, average scale
of the climate warming was 3-5 °C higher than our recent Holocene global average.
Owing to the warmer climate, the vegetation and other soil-forming factors also
changed and are confi rmed by the appearance of soil with a very distinct gray-black
humus horizon. Above it the next Wisconsin (or Würm) loess (115-11.7 kyr BP)
was deposited. Nothing more than the description of the buried soil hidden between
two layers of loess was known at that time of the end of the nineteenth century in
Russia and similarly in the midcontinental USA.
We identify the beginning of a new branch of science as well as a new scientifi c
subject in the virtually unknown and forgotten booklet of K.D. Glinka,
The Aims of
the Historical Pedology
(the title translated from Russian, published in Warsaw,
1904). The booklet offered a critical review of papers and topics of geologists and
geographers where the geological sediments were described in relation to plants and
to rather incomplete knowledge of soils. Since
palaios
is Greek for old, the new
branch of soil science was therefore named paleopedology and the broad family of
old soils obtained the name paleosols. Glinka was probably one of the fi rst scientists
to be infl uenced by Dokuchaev who was a geographer and geologist. Glinka
declared himself as a student of Dokuchaev and accentuated the relationships
