The physiographic regions of the world are a means of defining the Earth's
landforms into distinct regions, based upon the classic three-tiered approach
by Nevin Fenneman in 1916, that further defines landforms into: 1. physiographic
divisions; 2. physiographic provinces; and 3. physiographic sections. This
foundational model, which Fenneman used to classify the United States, was the
basis for similar classifications of other continents later, and is still
considered basically valid. Introduction
During the early 1900s, the study of regional-scale geomorphology was termed
"physiography". Unfortunately, physiography later was considered to be
a contraction of "physical" and "geography", and therefore synonymous
with physical geography, and the concept became embroiled in controversy
surrounding the appropriate concerns of that discipline. Some geomorphologists
held to a geological basis for physiography and emphasized a concept of
physiographic regions while a conflicting trend among geographers was
to equate physiography with "pure morphology," separated from its
geological heritage. . In the period following World War II, the emergence of
process, climatic, and quantitative studies led to a preference by many
Earth scientists for the term "geomorphology" in order to suggest an
analytical approach to landscapes rather than a descriptive one. In current
usage, physiography still lends itself to confusion as to which meaning is
meant, the more specialized "geomorphological" definition or the
more encompassing "physical geography" definition. For the remainder of this
article, emphasis will remain on the more "geomorphological" usage, which is
based upon geological landforms, not on climate, vegetation, or other
non-geological criteria. For the purposes of physiographic
mapping, landforms are classified according to both their geologic
structures and histories. Distinctions based on geologic age also correspond to
physiographic distinctions where the forms are so recent as to be in their
first erosion cycle, as is generally the case with sheets of glacial drift.
Generally, forms which result from similar histories are characterized by
certain similar features, and differences in history result in
corresponding differences of form, usually resulting in distinctive
features which are obvious to the casual observer, but this is not always the
case. A maturely dissected plateau may grade without a break from rugged
mountains on the one hand to mildly rolling farm lands on the other. So
also, forms which are not classified together may be superficially similar;
for example, a young coastal plain and a peneplain. In a large number of cases,
the boundary lines are also geologic lines, due to differences in the nature
or structure of the underlying rocks. = History=
19th-century The history of "physiography" itself is
at best a complicated effort. Much of the complications arise from how the
term has evolved over time, both as its own 'science' and as a synonym for other
branches of science. In 1848, Mary Somerville published her book Physical
Geography which gave detailed descriptions of the topography of each
continent, along with the distribution of plant, animals and humans. This work
gave impetus to further works along the field. In Germany, Oscar Peschel in
1870, proposed that geographers should study the morphology of the Earth's
surface, having an interest in the study of landforms for the development of
human beings. As the chair of geography in Bonn, Germany, Ferdinand von
Richthofen made the study of landforms the main research field for himself and
his students. Elsewhere, Thomas Henry Huxley's Physiography was published in
1877 in Britain. Shortly after, the field of "physical geography" itself was
renamed as "physiography". Afterwards, physiography became a very popular
school subject in Britain, accounting for roughly 10% of all examination
papers in both English and Welsh schools, and physiography was now
regarded as an integral, if not the most important aspect of geography.
In conjunction with these 'advances' in physiography, physically and visually
mapping these descriptive areas was underway as well. The early
photographers and balloonists, Nadar and Triboulet, experimented with aerial
photography and the view it provided of the landscape. In 1899, Albert Heim
published his photographs and observations made during a balloon
flight over the Alps; he is probably the first person to use aerial photography
in geomorphological or physiographical research. The block diagrams of
Fenneman, Raisz, Lobeck and many others were based in part upon both aerial
photography and topographic maps, giving an oblique "birds-eye" view.
20th century By 1901, there were clear differences in
the definition of the term physiography. "In England, physiography is regarded as
the introduction to physical science in general. It is made to include the
elements of physics, chemistry, astronomy, physical geography, and
geology, and sometimes even certain phases of botany and zoology. In
America, the term has a somewhat different meaning. It is sometimes used
as a synonym for physical geography, and is sometimes defined as the science
which describes and explains the physical features of the earth's
surface". By 1911, the definition of physiography
in Encyclopædia Britannica had evolved to be "In popular usage the words
'physical geography' have come to mean geography viewed from a particular
standpoint rather than any special department of the subject. The popular
Physical meaning is better conveyed by the word physiography, a geography term
which appears to have been introduced by Linnaeus, and was reinvented as a
substitute for the cosmography of the Middle Ages by Professor Huxley.
Although the term has since been limited by some writers to one particular part
of the subject, it seems best to maintain the original and literal
meaning. In the stricter sense, physical geography is that part of geography
which involves the processes of contemporary change in the crust and the
circulation of the fluid envelopes. It thus draws upon physics for the
explanation of the phenomena with the space-relations of which it is specially
concerned. Physical geography naturally falls into three divisions, dealing
respectively with the surface of the lithosphere – geomorphology; the
hydrosphere – oceanography; and the atmosphere – climatology. All these rest
upon the facts of mathematical geography, and the three are so closely
inter-related that they cannot be rigidly separated in any discussion".
The 1919 edition of The Encyclopedia Americana: A Library of Universal
Knowledge further adjusted the definition to be "Physiography, now
generally recognized as a science distinct from geology, deals with the
origins and development of land forms, traces out the topographic expression of
structure, and embodies a logical history of oceanic basins, and
continental elevations; of mountains, plateaus and plains; of hills and
valleys. Physical geography is used loosely as a synonym, but the term is
more properly applied to the borderland between geography and physiography;
dealing, as it does, largely with the human element as influenced by its
physiographic surroundings". 21st-century
Even in the 21st century, some confusion remains as to exactly what
"physiography" is. One source states "Geomorphology includes quaternary
geology, physiography and most of physical geography", treating
physiography as a separate field, but subservient to geomorphology. Another
source states "Geomorphology refers to the study of the surface features of the
earth. It involves looking at the distribution of land, water, soil and
rock material that forms the land surface. Land is closely linked to the
geomorphology of a particular landscape", regarding physiography as
synonymous with geomorphology. Yet another source states "Physiography may
be viewed from two distinct angles, the one dynamic, the other passive". The
same source continues by stating "In a large fashion geodynamics is intimately
associated with certain branches of geology, as sedimentation, while
geomorphology connects physiography with geography. The dynamic interlude
representing the active phase of physiography weaves the basic threads of
geologic history." The U.S. Geological Survey defines physiography as a study
of "Features and attributes of earth's land surface", while geomorphology is
defined separately as "Branch of geology dealing with surface land features and
the processes that create and change them".
Partly due to this confusion over what "physiography" actually means, some
scientists have refrained from using the term physiography because the
definitions vary from the American Geological Institute's "the study and
classification of the surface features of Earth on the basis of similarities in
geologic structure and the history of geologic changes" to descriptions that
also include vegation and/or land use. See also
List of the physiographic regions of the world
References This article incorporates text from a
publication now in the public domain: Chisholm, Hugh, ed.. Encyclopædia
Britannica. Cambridge University Press.