Over in 1850 and in 1870 had

Over the period of modern history, geography had become more
widely accepted as its own subject. Within this subject there have been very
influential figures whose theories and studies have changed the face of the
subject and have heavily influenced future geographers. In this essay I’ll look
at some of the figures that I believe are some of the most influential in the
subject; this consists of W.M. Davis, Louis Agassiz, Charles Darwin, Alfred
Wegner and Milutin Milankovitch.

The first of the influential figures I’ll be looking at is
William Morris Davis. W.M. Davis, born in Philadelphia in 1850 and in 1870 had
graduated from Harvard with a masters in engineering. He was most acclaimed for
his theory on the “geographical cycle”. The geographical cycle was by far the most
influential geographical concept introduced by Davis. For him the present-day
landscape resulted from a long-continued and orderly development. To understand
it, it was necessary to know the geological structures, the processes which
operate on the surface, and the duration of their formation. He held that the
present landscape could be understood only by understanding its past and,
equally, that an understanding of present-day landscape was a key to an
interpretation of at least some earth history. Davis assumed that a river
valley has progressed through one or more cycles, a complete cycle being marked
by youth, maturity, and old age as the river valley is worn lower and lower
into a landmass. In each stage the river and its valley displayed certain
distinctive characteristics. Furthermore, a cycle might be interrupted by
uplift of the land, which would revitalise the river and allow it to impose the
beginnings of a new cycle on the remains of an older one. The idea of youth,
maturity, and old age in a valley, first presented in the “Rivers and Valleys
of Pennsylvania,” was extended to embrace large landmasses. (Encyclopedia.com,
2017) W.M. Davis also states that, “Process cannot,
however, complete its work instantly, and the amount of change from initial
form is therefore a function of time. Time thus completes the trio of
geographical controls, and is, of the three, the one of the most frequent application
and of a most practical value in geographical description.” (Davis,
1973) Around the time Davis published his theory, it was widely challenged,
especially by German geomorphologists such as Albrecht Penck, Professor of
Physical Geography at the University of Vienna and later of Geography at
Berlin, and more particularly his son Walther Penck. Davis had been widely
accepted as one of the great geographers in America and by 1904 he had founded
the Association of American Geographers. Davis’s approach to geography can be found in the work of many well-known
followers. These included Ellsworth Huntington, famous for his study of tree
rings as these related to changes in climate. Isaiah Bowman pursued physical
geography as well as human geography and served in key positions, including
Director of the American Geographical Society and president of Johns Hopkins
University. Mark Jefferson, another follower of Davis, was one of the most
prolific scholars of his time at the Michigan State Normal College at Ypsilanti,
he trained thousands of geography school teachers. (Taylor & Francis, 2017)

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Figure 1 (Huggett, 2011)

 

 

 

 

 

Louis Agassiz is the next
influential geographical figure I’ll be writing about. Agassiz was born on May
28th, 1807, in Haut-Valley, Switzerland and studied at the
universities of Zurich, Heidelberg and Munich, chasing a profession in
medicine. However, he studied natural history and specialised in botany. By
1829, Agassiz had obtained a doctorate in Philosophy at Erlangen and the
following year received another doctorate in medicine at Munich. Agassiz
initially was a palaeontologist and expert in fossil fish until he shifted his
interest and study to glacial geology. It was in the 1830’s, Jean de
Charpentier began to assemble the scientific evidence for former alpine
glaciation. Initially, Louis Agassiz was one of those to have disbelieved de
Charpentier. Eventually, through his own observations, Agassiz came to accept
the concept of former glaciation and carried this concept much further. In
1837, Agassiz proposed that vast sheets of ice had once covered much of the
northern hemisphere. Initially, this was a radical suggestion as at the time
ice sheets in Greenland and Antarctica were unknown to them. Eventually, through
this, he was able to establish a name and reputation in academic circles and
added weight to his subsequent “glacial theory.” Unsurprising that it
took so long for Agassiz’s theory to become widely accepted, this was because
it required a number of advances such as, the description of existing glaciers,
the recognition that landforms within a few miles of ice margins are of glacial
origin, the notion that landforms tens of miles away may have a glacial origin and
features in areas completely lacking glaciers may have been glacial in origin. Despite
strength of the evidence, and the reputation of proponents, Agassiz’s theory
still met with opposition and after a period of quiescence, interest and
support for Agassiz’s theory increased and his “glacial theory” was finally
accepted by most. It was his visit to Britain that represented a turning point
in the debate. Agassiz relied heavily on the topicality of his fieldwork in
Britain to persuade the British academic community. His concluding talk at RGS
referred to the pattern of erratic and striations illustrating the radial flow
of ice from upland areas, similarity of till in Scotland to debris found at the
margins of Alpine glaciers and parallel roads of Glen Roy representing
shorelines of icedammed lakes. The glacial geology broke away from any
confusion with Noah’s flood and developed as a separate branch of research and
led to the wide acceptance of his work. Agassiz
undertook detailed studies of glacier movement in Switzerland in the 1840s, and
he influenced James D. Forbes, a Scotch physicist, to begin similar
glaciological research in the French Alps. Forbes established that glaciers
move in part by internal “viscous” deformation, in contrast to the
more popular dilatation or regelation theories of the day. Later on in the
future, Agassiz’s work had been developed by key figures in geography such as,
Andrew Ramsay who provided detailed descriptions of glacial phenomena in Wales
and Archibald Geikie who provided a detailed paper on the structure of glacial
drifts in Scotland.

Another key figure in geography is Charles Darwin. Darwin
was born on the 12th of February 1809 and initially studied medicine
at Edinburgh but later found interest geology. Darwin’s evolutionary concept of change over time was applied
by W.M. Davis in the concept of geographic cycle. Davis developed a similarity
between organic life and evolution of landforms. He advocated that “landforms
evolve like the evolution of organic life”. The cycle of erosion has been
defined by him as ‘geographical cycle’ is the period of time during which an
uplifted landmass undergoes its transformation by the process of land
sculpture, ending into a low featureless plain, a peneplain. (Your Article Library, 2017) However, Darwin’s most credited work
was his idea of natural selection, which completely changed the concepts and
understanding of biodiversity in geography. In this, he proposed that species can change
over time, that new species come from pre-existing species, and that all
species share a common ancestor. Darwin’s concept of natural selection
consisted of three observations. The first was that traits are often heritable.
In living organisms, many characteristics are inherited, or passed from parent
to offspring; Darwin knew this was the case, even though he did not know that
traits were inherited via genes. The second was more offspring are produced
than can survive. Organisms
can produce more offspring than their environments can support and thus, there
is competition for limited resources in each generation. The final observation
was offspring vary in their heritable traits. This means that the offspring in
any generation will be slightly different from one another in their traits, and
many of these features will be heritable. From these observations Darwin
concluded that in a population,
some individuals will have inherited traits that help them survive and
reproduce, given the conditions of the environment, such as the predators and
food sources present. The individuals with the helpful traits will leave more
offspring in the next generation than their peers, since the traits make them
more effective at surviving and reproducing. Because the helpful traits are
heritable, and because organisms with these traits leave more offspring, the
traits will tend to become more common in the next generation. Over
generations, the population will become adapted to
its environment as individuals with traits helpful in that environment have
consistently greater reproductive success than their peers. To this day,
Darwin’s work on natural selection remains influential in both geography and
biology; and has been accepted in science as a factual process.

Figure 2 (Acquisio Blog, 2017)

 

 

 

 

 

 

 

 

 

The fourth influential figure in
geography is Milutin Milankovitch and his development of one of the most significant theories relating
Earth motions and long-term climate change, originally suggested by James Croll.
In 1864 Croll wrote about
orbital change and the ice of the Ice Ages using both the eccentricity cycle
and the precession cycle.  Later in 1875 he took into account the
obliquity cycle.  Milankovitch, being a mathematician, took Croll’s
work and set out to develop a mathematical theory of climate change.  His
theory states that as the Earth travels through space around the sun cyclical
variations in three elements of Earth-sun geometry combine to produce
variations in the amount of solar energy that reaches Earth.  These three
elements that have cyclic variations are eccentricity, obliquity, and
precession. The eccentricity defines
the changes in the orbital shape, which occurs every 100,000 years. The shape of
the Earth’s orbit determines the amount of incoming solar radiation due to
changes in the distance from the Earth to the sun. The shortest distance is
the perihelion and the longest
distance is the aphelion.
Earth is more than 3 million miles further from the Sun at the aphelion than at
perihelion. Obliquity, the second of the
Milankovitch cycles, is the earth’s tilt relative to the earth’s orbit around
the sun. The tilt away from the axis changes from 22.1° to 24.5° over a
period of 41,000 years. When the tilt becomes larger, the seasons are more
extreme, with more severe winter and summer weather.  When the tilt is
smaller, the seasons are milder and less different from each other. Finally,
the precession, is how much the earth wobbles on its axis. The result is
that the North Pole on earth changes where it points to the sky.  At
present it is pointing at what we call Polaris, the Northern Star. 
However, 13,000 years ago it was pointing somewhat away from Polaris. The
position of the North Pole on the sky forms a circle that is traced out every
26,000 years. The combination of the precession with whether the earth is nearer
or further from the sun can affect the severity of the seasons in one
hemisphere compared to the other. (Climate.ncsu.edu,
2012) However, for about 50 years, Milankovitch’s theory was largely neglected.
This was until 1976, when a study that was published examined deep-sea sediment
cores and found that Milankovitch’s theory did resemble to periods of climate
change. The authors of the study were able to extract the record of temperature
change, going back 450,000 years and found that major variations in climate were
closely linked to Milankovitch’s eccentricity, obliquity and precession of the
Earth’s orbit.

Figure 2 (Villanueva, 2017)

 

 

 

 

 

 

 

The final influential
figure I’ll be looking at is Alfred Wegner, who was a geophysicist and
meteorologist. Wegner was most famous for his theory on continental drift in
1912, which he believed was the reason why there was the same fossils found in
different continents. This theory suggested that all the continents were joined
up together in what he described as a “Urkontinent”, before eventually breaking
up and moving to their current positions. Despite the fact that Wegner’s
assumptions on fossils and rocks were correct, he was wrong on some key points.
For example, he thought that continents could have possibly smashed through the
oceanic crusts and that the continents moved due to Earth’s rotation. However,
at the time geologists quickly disregarded his theory due to insufficient
evidence he provided at the time. Therefore, scientists at the time tried to
disprove Wegner’s finding of identical fossils in different continents by
stating there was a ‘land bridge’ that connected the continents. It wasn’t
until the 1960s, when Wegner’s concept of a united continent was proven;
however, it was found that continents move due to tectonic activity and the
continent now known as Pangea was formed roughly 300 million years ago.

Figure 4 (Society and
Society, 2017)

 

 

 

 

 

 

To conclude, I believe that
out of the influential figures I’ve mentioned, Darwin had the greatest impact.
One reason is due to his vast collection of work, as before his theory on
natural selection he’d already produced work on geology, based on W.M. Davis’s
geological cycle. Furthermore, his theory on natural selection has had one of greatest
impacts on modern day science and had answered many biological questions.
Additionally, at the time Darwin had faced the most backlash on his theory than
most scientists due to the religious concepts during those times; however, his
theory was proven correct and is regarded as factual information. Darwin has
also left one of the greatest legacies behind and is one of the most well-known
scientists to this day.