We are entering the era of geography, an era when geographical thinking is essential for
making sense of a globally interconnected world, a bold claim for a discipline that
is defined more by a perspective than by a particular topic.
But it's an integrated perspective that can help us understand everything from the movement
of the tiniest brain of sand to the clashing of continents, to the rise and fall of nations,
to the trekking of hurricanes, to the distribution of material well across the globe.
I am Alec Murphy, and I'm going to show you how this much ignored subject in 20th century
America, rose to a position of prominence in the 21st century.
This is the story of physical geography, making sense of planet Earth.
In this first program, inventing the tools of geography, we shall see how geography came
of age.
Geographical thinking is certainly focused on why physical features and processes occur
where they do.
But it is also uniquely concerned with how the place on the planet where something occurs
affects what happens.
Geographical thinking brings an analytical perspective to bear on the world.
Leading the 7 billion people living on the planet, as part of an interconnected web of
Earth processes, and developing human cultures that coalesce in distinct ways, coalesce in
distinct ways depending on where you are.
There is great power in geographical thinking, deeply addressing the issues and challenges
of the 21st century.
In the 21st century, with the deluge of data coming from all sorts of automated sources,
for example, I believe that geography is going to be the way we integrate what we know
about the social and natural world.
There are many ways in which good geographical thinking is a skill set that will be needed
by individuals, needed by companies, needed by governments.
For example, at the technical end, geographic information systems, some spatial computer
science is ubiquitous today.
Pull out your iPhone and go to Google Maps.
That's geography.
Who doesn't value or require that information now, and it's not just a map, it's the incorporation
of information in a spatial context.
At the global scale, who can deny that a correct and thorough understanding of the Middle East,
for example, isn't essential to all of our interests, not just for people in Libya or
Syria or Iraq, but to the world as a whole.
That's geographical thinking.
There are always going to be questions that require us to understand how the different
parts of the Earth system work together, and those people who are able to understand how
these things fit together, or to predict how they fit together, are going to be those
that can influence decision-making.
It's natural that those people who can understand those relationships are going to be the ones
that hold the future in their hands.
What distinguishes geography from all other disciplines is our emphasis on space.
Global thinking, understanding spatial associations, flows, patterns.
Good geographical thinking is absolutely essential to every country, to its policies,
to its foreign policy in particular, and to its economy.
We have a lot of environmental and resource problems we're facing.
Most of them involve both the natural system and how it operates, but also people, how
people are going to respond to it, how people can adapt, what changes are feasible.
To understand that, we really have to bring the natural sciences and social sciences
together.
It's a hard task.
There are really different modes of thinking.
Geography is the discipline that fosters the interaction between those two different modes
of thinking.
Well, I've heard, of course, the world is flat, and that is that we don't have much
geographic differentiation.
I actually have heard people say that there is no more geography.
When you actually then step back and look at the world, we can see an awful lot of differences
in people, in the environment, in distribution of wealth, distribution of freedom even.
There's huge differences in the world.
We can't afford not to be aware of the geographic differences that still exist on the planet
and to utilize those in our thinking, and I think we can eventually utilize them to
make a much better world.
So I don't really think the world is flat.
There's still lots of topography.
Ever since the dawn of humankind, we have tried to make sense of the world that we find
ourselves in.
What is my place in my family, in my culture, in the landscape in which I live?
And today, what is my place in my community, my country, in the world, and in the universe?
Rivers today often like to answer these age-old questions by saying, "You're at a particular
place on a modest-sized planet circling a medium-sized sun."
A sun located somewhere on the edge of a spiral galaxy of 300 billion suns, in a universe
of over 100 billion galaxies.
A universe that is 13.7 billion years old.
However, go back just a few hundred years, and this view of our place in the cosmos
would have been unimaginable.
Many thought the Earth was at most a few thousand years old.
They assumed that the landscapes many features, oceans, mountains, lakes, canyons, and rivers
would have been the same then as it is now.
People believed that these landforms were there from the beginning.
Of course, the occasional river flooding and volcanic eruptions modifying the surface
of the Earth were acceptable anomalies.
Earth and everything about it was seen as static.
Today, a mere 300 years later, it is common knowledge that the planet is incredibly old.
Every aspect of the planet's surface and its atmosphere is constantly moving, ever-changing.
Understanding these changes has become critical to understanding every human development, agriculture,
language, religion, science, culture, technology, economics, even the modern creation and distribution
of wealth.
So geography is not only about having a name for where you are, but more importantly, it's
about making sense of where you find yourself.
So if you find yourself on the shores of the Savannah River in Georgia, and a huge
container ship comes by, do you know what that's about?
Geographical thinking can help provide the answer.
Here's the most famous geographic icon in all of Utah, the delicate arch.
How did such a really bizarre piece of rock appear here, looking like this?
Geographical thinking can answer this now, but it took 300 years of geographical discoveries
to pave the way for this understanding.
So how did this dramatic recognition come about?
It came about through a recognition that Earth's features and our social structures
are not given, but are ever-changing.
It's an extraordinary story of incredible scientific discoveries.
In these rocks behind me, you can clearly see layering and banding, layer upon layer.
With brilliant geographical reasoning, 17th-century Danish naturalist Nicholas Stenow, looking
at the same situation, deduced the three fundamental laws of geology.
The most important deduction is first, the law of superimposition.
It states that when a lower layer was formed, the upper layers did not exist.
Therefore, the lower layers are always older.
This remains true whether the layers were formed by molten lava or by the laying down
of sediments in a river.
The next law is the principle of original horizontality.
It is a common observation in the field that layers of rock are not parallel to the horizon,
but are often tilted, such as this dramatic example along the foothills of the Rocky Mountains.
Stenow stated simply that all rock layers were originally horizontal.
The result of accepting this law was that further geological forces, such as mountain
building, were needed to explain any strat deviation from the horizontal.
The last law is the principle of discontinuity.
For example, when a volcanic eruption cuts through existing strata, or crystals form
in a rock matrix, Stenow stated that the discontinuity must have occurred after the
base strata were formed.
In other words, the discontinuity was younger.
An implication of all these laws is that the Earth was not created in one moment.
But how old was it?
Of all the 19th century scientific debates, none were more hotly contested than how old
is planet Earth.
And how did the surface come to be as it is?
Finally, how did it come to be a patchwork of mountains, badlands, flat plains, hills,
rivers, lakes, and oceans?
In his seminal 1830 publication, Principles of Geology, Charles Lyell answered the second
part of the debate.
In doing so, he laid the foundation for the study of landforms and the processes that
shaped them, a central concern of physical geography, prompted by a growing fossil record
that revealed creatures that no longer existed.
Scotsman James Hall and other geologists were performing laboratory experiments that produced
crystals, crystals like those found in rocks.
To their minds, the physical character of the surface of the Earth must have resulted
from some natural process, but what was it?
Before Lyell's publication, there were two competing scientific theories for what happened.
One, the neptunus theory, named after the Roman *** of the sea, held that the Earth was
totally covered by water, and its features resulted from the recession of the floodwaters.
The other, the plutoniumist, named after the Roman *** of the underworld, advanced the
idea that Earth's features resulted from a cataclysmic event of intense heat and pressure.
What they had in common was that both were sudden singular episodes, and then were done.
Rather than searching for a one-time event, Lyell brilliantly argued that scientists should
look to the forces and play today, volcanism, wind, and water erosion.
What was happening now was the key to what happened in the past.
Lyell turned out to be right.
The present as the key to the past, of course, is a key intellectual tool used by Earth scientists
to try to unravel the evidence that they find buried in sedimentary deposits on the surface
of the Earth, and the argument being that although the processes we see operating here
now may have operated in the past at different rates, they nonetheless were the same process.
It is that the Grand Canyon, for example, is a product of processes we see operating
right now, today, but that it operated over immense time periods.
It is not necessarily the product of Paul Bunyan dragging his axe over the surface of
Northern Arizona, which in fact was one of the explanations originally.
However, not all features could be explained by such obvious forces such as water and wind
erosion.
At the same time Lyell proposed his geographical theory, naturalists who traveled to high mountain
ranges were well aware of glaciers and their powerful effects as they moved across the
mountain landscape.
They also noticed boulder fields containing rocks from nearby mountains, and huge gravel
deposits far from any rivers.
How could that be?
In 1837, a Swiss-born pastor, Louis Agassiz, presented what he called the discovery of
a great ice age to the Swiss society of natural scientists.
He argued that a massive ice age had wiped out the megafauna of mastodons, saber-tooth
tigers, and other large animals found in the recent fossil record.
While incorrect about the demise of the megafauna, his idea of an ice age turned out to be true.
Assuming that ice once covered parts of Wisconsin, producing gravel deposits called drumlands
raised new questions.
If ice once covered much of mid-latitude North America, it must have been very cold for a
long time.
From then on, climatology, the study of climate change, would become an important part of geography.
As for the extinction of the megafauna, such as the saber-tooth tigers and mastodons, a
definitive explanation has still not been found.
So now, geographers had another force that was shaping the landscape over long periods
of time, glaciation.
But these forces were largely ones that helped explain how mountains became eroded and planes
were formed.
Geographers also needed some way to account for the creation of mountains in the first
place.
At the start of the 20th century, a number of Earth geophysical phenomena, such as earthquakes,
including the 1906 tremor that devastated San Francisco.
And volcanic eruptions also puzzled geographers.
Surprisingly, these phenomena would be brought together under one umbrella theory 60 years
later.
Abraham Ortellius, a 16th century Flemish cartographer, a person we geographers recognize as the
creator of the first modern atlas.
Notice the similarities between Africa's West Coast and South America's East Coast.
It was easy to imagine South America's bulge fitting into West Africa's indentation like
pieces of a jigsaw puzzle, trying to make sense of this observation, or tellius asked
the geographical question, could they have been joined sometime in the distant past?
At the same time, maps also helped to show that earthquakes and volcanoes occurred in
specific regions on the planet, regions often associated with mountains, where all these
phenomena related.
In 1912, the German physical geographer Alfred Wegener, in an attempt to answer Atilius'
question, proposed that all the continents were once joined into one giant continent
called Pangaea.
Then over vast geological time, they had drifted into their present-day positions.
This meant that the outer layer of the planet, the crust, had to be cut into large movable
plates.
Plate tectonics, as it was called, required that geography totally reshape its explanations
of Earth processes.
Plate tectonics was such a revolutionary change in how we viewed landform processes and the
evolution of the Earth's surface, that it forced geomorphologists, as well as all of
the geological sciences, to rethink how the Earth functions.
It meant a revision of some long-standing thought.
It perhaps could be likened to a Koonian revolution in the sciences, that the normative science
had to be put aside and a new set of ideas had to be adopted.
This idea of continental drift initially received little early support, but eventually, it
explained the San Francisco earthquake.
It was the result of the North American and Pacific Ocean plates sliding against each other.
Indeed, Artilius was right.
Africa and South America were once joined.
We can now see in retrospect that by the middle of the 19th century, geographers were
well on their way to understanding that the forces that shaped the planet's landscapes
are the same forces occurring today.
The last piece of important understanding came when it became clear that features that look
the same might have very different histories or origins.
If we look around the U.S., there are several areas that are quite flat, and they're all
for different reasons.
Florida is flat because it's a shallow sea bottom.
When we go to North Dakota, it's flat because it was a glacial lake, and sediments collected
and created a very flat bottom, makes it an agricultural land, of course.
Illinois is flat because of glacial outwash.
These were bold and powerful discoveries about processes shaping the planet's landscape
features.
Geographical discoveries that made for amazing advances and the effort to make sense of
the world we lived in.
But that was not enough.
Geographers needed an accurate way of pinpointing every place on the planet.
A set of conventions in map making that would be accepted worldwide, allowing geographers
to keep accurate records of how the surface of the Earth was changing.
By the end of the 18th century, a network of intersecting latitudinal parallels and longitudinal
meridians forming a geographical grid over the entire surface of the Earth was in place.
Every place on the planet's surface could be referenced by a set of coordinates.
In the United States in the 18th and 19th centuries, explorers map trails and army engineers
surveyed government lands, recognizing the importance of good geographical information.
Two agencies were established to provide more detailed large-scale mapping.
They were the U.S. Geological Survey and the United States Coast Endiodetic Survey.
Most countries around the world set up similar agencies.
Let's bring this all together and see how one of these forces, glaciation, shaped features
such as the famous peaks of the Great Tetons in northern Wyoming and set the stage for
the emergence of everything we call human.
One of the really interesting things about the time we live in, that is the time since
the last ice age, is of course the ascent of human culture.
In terms of the number of people that we have on the planet, from a period of time when
it might have been measured in a few millions at most, to period now where we have 7 billion
people.
That rise was facilitated by, of course, the development of agriculture and the development
of material culture, cities, our trade networks, our science, our technologies.
It really is an incredible, incredible period the last 12,000 years.
What propelled us forward like that?
Part of it is, of course, the climate that we have.
The end of the last ice age, we opened up vast tracts of the world that were covered
by ice.
Places like the near and middle east became moisture.
They were more capable of supporting agriculture.
And for the first time during an interglacial period, we had modern humans present in large
parts of the world.
And clearly, our species, the modern humans, were able to take advantage of that interglacial
warmer world.
So human activity became part of geography.
Indeed, the last major phase of geography to develop was a branch of the discipline
called human geography.
Will Graf has been a pioneer in modern geographical thinking and has studied its history as it
gradually separated from geology in the 19th and 20th century.
Geography at least in the United States grew out of a close association with geology.
And for many decades beginning in the middle 1800s, geographers who were interested in
people diverged a bit from geologists who were much less interested in people and much
more interested in earth systems.
So over a long period of emergence during the 20th century, human geography became increasingly
important.
In some cases, associated very closely with anthropology.
By the time we got to the middle part of the 20th century, though, human geography began
to develop its own techniques, its own research questions.
And from my standpoint, probably because I was there at the time, I saw the emergence
of human geography in the 1960s and 1970s as a true discipline of intellectual activity.
Thanks for the delicate arch in Utah, here's how it came to be.
At Arches National Park, you have a number of circumstances that have come together and
acted in concert to create the arches.
The first thing is that you have a couplet of deposits below is the very tight mudstone
and claystone of the Carmel formation.
This is overlain by wind-blown sand of the Entrada sandstone, which is very porous where
water can move through readily.
And long before this area was exposed to erosion, these two deposits acted to conduct groundwater
along the base of the Entrada sandstone.
And what this did is it weakened the cement between the sand grains in the Entrada and
this caused little pockets of it to become weak.
Well because of this previous weakening of the cement in the sand grains, now they weather
out into these holes and they break through these thin fins to create the many arches
that you find here in this national park.
And there's more arches in this national park than any comparable size landscape on
the planet.
And what about that container ship cruising along the Savannah River?
The ship is carrying trade goods between the port of Savannah, Georgia, the fourth largest
container seaport in the United States.
Carrying trade goods between Savannah and destinations such as India, the Middle East
and the Mediterranean Basin.
To make sense of this, we need accurate maps showing how a ship this large moves across
such great distances.
Join me, Alec Murphy, as we explore portraying the Earth in the next episode of Physical
Geography, Making Sense of Planet Earth.
As for the age of planet Earth, the major question that drove much of early geographical
investigation, the answer is approximately 4.5 billion years old.
Thanks for watching!