|Professor Iain Stewart examines
the role of geology in the history of mankind in this
documentary program. Each of the classical elements
plays a role - for instance, he points out that mankind
has been drawn to fault lines for centuries, since this
is the best place to find minerals, oil, soil suitable
for farming, etc. But with these riches comes great
danger, of course, since locating communities on the
fault lines makes them vulnerable to earthquakes.
Subsequent episodes review the cycle of freshwater, the
force of the wind, and fire both as a source of energy
and a terrifying force of nature. From crystal caves in
Mexico to holes in the Iranian desert and a mysterious
lake in Oregon, Stewart travels the globe to hammer his
|Deep Earth |
Beneath the Crust
In this first episode, Iain explores the relationship between the deep Earth and the development of human civilisation. He visits an extraordinary crystal cave in Mexico, drops down a hole in the Iranian desert and crawls through 7,000-year-old tunnels in Israel. His exploration reveals that throughout history, our ancestors were strangely drawn to fault lines, areas which connect the surface with the deep interior of the planet. These fault lines gave access to important resources, but also brought with them great danger.
|Water | Water
This time he explores our complex relationship with water. Visiting spectacular locations in Iceland, the Middle East and India, Iain shows how control over water has been central to human existence. He takes a precarious flight in a motorized paraglider to experience the cycle of freshwater that we depend on, discovers how villagers in the foothills of the Himalayas have built a living bridge to cope with the monsoon, and visits Egypt to reveal the secret of the pharaohs' success. Throughout history, success has depended on our ability to adapt to and control constantly shifting sources of water.
|Wind | The Skies
Iain sets sail on one of the fastest racing boats ever built to explore the story of our turbulent relationship with the wind. Travelling to iconic locations including the Sahara desert, the coast of west Africa and the South Pacific, Iain discovers how people have exploited the power of the wind for thousands of years. The wind is a force which at first sight appears chaotic. But the patterns that lie within the atmosphere have shaped the destiny of continents, and lie at the heart of some of the greatest turning points in human history.
|Fire | The Gift
Iain explores man's relationship with fire. He begins by embarking on an extraordinary encounter with this terrifying force of nature - a walk right through the heart of a raging fire. Fire has long been our main source of energy, and Iain shows how this meant that the planet played a crucial role in Britain's industrial revolution, whilst holding China's development back. Along the way he dives in a mysterious lake in Oregon, climbs a glacier of salt, crawls through an extraordinary cave in Iran and takes a therapeutic bath in crude oil.
|Human Plaet |
The Human Era
Professor Iain Stewart explores the most recently established force - humans. It's easy to think of the human impact on the planet as a negative one, but as Iain discovers, this isn't always the case. It is clear that humans have unprecedented control over many of the planet's geological cycles. The question is, how will the human race use this power?
|Earth Revealed shows the
physical processes and human activities that shape our
planet. From earthquakes and volcanoes to the creation
of sea-floor crusts and shifting river courses, Earth
Revealed offers stunning visuals that explain plate
tectonics and other geologic concepts and principles.
Follow geologists in the field as they explore the
primal forces of the Earth. This series can also be used
as a resource for teacher professional development.
to Earth - Questions
Beginning by comparing surface conditions on the planets Venus and Mars with the living landscapes of the Earth to highlight how unique the Earth is, the episode describes the goal of the study of geology and introduces major topics the series addresses, including the Earth's heat engines, plate tectonics, volcanism, earthquakes and seismology, erosion, and natural resources such as groundwater.
Planet - Questions
The episode discusses the development of astronomical theory, including the geocentrist views of astronomers in ancient Greece and the discoveries of Copernicus, Galileo Galilei, Johannes Kepler, and Isaac Newton. It also describes the formation of the Solar System and the physical evolution of the Earth over time, including its internal structure – through the process of planetary differentiation – and development and retention of an internal heat engine, its atmosphere, its hydrosphere, and the appearance of life.
Plate Tectonics: The Unifying Model
Interior - Questions
The episode introduces geophysics, discussing how geophysicists study what lies beneath Earth's surface, using studies of seismic waves, variations in temperature, magnetic fields, gravity, and computer simulations to create models of structures deep in the earth. The episode also discusses paleomagnetism and the phenomenon of magnetic field reversals.
Sea Floor - Questions
The episode explains how geologists study the sea bottom, using research submersibles and indirect methods, getting glimpses of volcanic activity; underwater formations such as the continental shelf, continental rise, slopes, canyons, abyssal plains, and mid-ocean ridges; and life forms that thrive at extreme depths in a world of intense pressure and total darkness. The episode examines subduction, seafloor spreading, hydrothermal vents, and the metallic resources found on the ocean bottom.
Birth of a Theory - Questions
The episode examines the theory of plate tectonics and its development from its beginnings in the work of Alfred Wegener in the early 20th century through its maturation and acceptance in the 1960s. Topics covered include the prehistoric supercontinent Pangaea, continental drift, seafloor spreading, subduction trenches, paleomagnetism and magnetic field reversals, transform faults, and mantle convection.
Dynamics - Questions
The episode examines the movement and interaction of tectonic plates and discusses the many geologic formations and phenomena that result from it, including faults, rift valleys, convergent plate boundaries, divergent plate boundaries, volcanism, subduction, and hotspots. It also discusses the lithosphere and asthenosphere and how they interact, mantle plumes, and the debate among geologists over what drives the motion of plates.
Building and the Growth of Continents - Questions
The episode discusses the process of orogeny (mountain building) and the role plate tectonics play in it, cratons and their formation, the growth of continents through accretion, the erosion of mountains, isostasy, how different types of rock form in the course of orogeny, and how rock types change over time through the rock cycle.
Structures - Questions
The episode explores rock layers, outcrops and geologic cross-sections, sedimentation and sedimentary layering, the principle of original horizontality, major structures of rocks – including fractures, joints, faults, folds, anticlines, synclines, and uncomformities – and the methods used to study them. It also examines tectonic force and the different types of stress involved in the formation of geologic structures and the deformation of rocks. Finally, it describes how geologic structures can trap petroleum, natural gas, and water and the resulting importance of the study of geologic structures in economic geology.
The episode discusses the forces that create earthquakes, explaining faults, seismic waves, the transfer of energy from an earthquake's epicenter, the method of determining an epicenter's exact location, how seismic waves affect different buildings differently, and the histories of the seismograph and Richter scale. It also describes devices under development in 1992 to study earthquakes with an eventual goal of predicting them.
Geologic Time and Life
Time - Questions
The episode describes the immensity of geologic time, the timeline of major geologic events in the Earth's history, the relationship between the geologic timeline and the history of life on Earth, and the use of fossils, radiocarbon dating, and uranium in radiometric dating to determine the age of rocks, fossils, and the Earth itself. The episode highlights the contributions of James Hutton and Ernest Rutherford and discusses unconformities, uniformitarianism, the law of superposition, the principle of original horizontality, cross-cutting relationships, relative age dating, and paleontology.
Through Time -
The episode focuses on how the fossil record reveals the diversity and development of life on Earth, examining the traces left by single-celled prokaryotes and eukaryotes, early plants, animals, and the progression of life forms over time through the "Cambrian explosion" and the Paleozoic, Mesozoic, and Cenozoic eras, as well as the fossils found at the La Brea Tar Pits; and the theory of evolution. The episode discusses the connections between life on Earth and atmospheric gases, climate change, and the formation of rocks, as well as biological functions, mass extinctions, and the effects humans have had on the biosphere.
The Rock Cycle
The Materials of Earth - Questions
The episode examines the variety of minerals, their atomic and crystalline structures, and their physical properties such as color, hardness, luster, cleavage, and streak. It also describes how petrologists section rocks and discusses hydrothermal solutions, the precipitation of metallic minerals, gems, precious metals, the formation and excavation of ores, and the value of silicates.
The episode describes volcanic processes, how tectonic plate boundaries are related to volcanism, and how volcanoes provide geologists with clues as to what is happening within the Earth. It also surveys the various types of volcanic eruptions, craters, cones, and vents, lava domes, magma, rift zones, volcanic rock, the relationship of volcanoes to ore deposits and geothermal energy, and the clues that volcanologists use to predict eruptions.
Igneous Rocks - Questions
The episode examines the process in which magma seeps into crevices in existing rock and cools to form dikes of intrusive igneous rock without ever extruding onto the Earth's surface and how plate tectonics play a role in the process. It also discusses the formation and types of magma, xenoliths, batholiths, igneous differentiation, and how an understanding of igneous rock helps geologists understand the Earth's history. Geologists explain the types and textures of intrusive igneous rocks such as granite, obsidian, and quartz.
and Soils - Questions
This episode shows how weather, climate, chemicals, temperature, and type of substrate play a role in rock erosion and the formation of soil. It discusses mechanical and chemical weathering of rocks, rock exfoliation and fracturing, the acidification of rainwater and formation of acid rain, soil horizons, the Dust Bowl of the 1930s, the effect of irrigation on soils, windbreaks, and the importance of soil as a natural resource. It also shows how a soil conservation plan is developed and put into action at a farm in California's Mojave Desert.
Wasting - Questions
The episode explains the phenomenon of mass wasting — the downslope movement of earth under the influence of gravity. It discusses various factors involved in mass wasting, including the rock's effective strength and pore spaces, and different types of mass wasting such as creep, slump, and landslides, as well as rockslides, debris flows, and mudflows. It explains the influence of slope angle, water and rain, and human activities such as the construction of buildings and roads, on mass wasting. It also explains how engineering geologists assess slope stability.
Rocks: The Key to Past Environments - Questions
The episode describes how exposed layers of sedimentary rock allow scientists to discern the Earth's geologic past, the movement of sediment and its deposition and how energy affects both transportation and deposition of sediments, how weathering and erosion influence the composition of sediments, sorting, sedimentary beds and cross-bedding, and the production of sedimentary rocks through the processes of lithification, compaction, and cementation. It also discusses organic components and the economic importance of sedimentary rocks.
Rocks - Questions
The episode describes how the weight of a mountain creates enough pressure to recrystallize rock, thus creating metamorphic rocks. It outlines the recrystallization process and the types of rock it can create, including claystone, slate, schist, and garnet-bearing gneiss, and it explains the relationship of metamorphic rock to plate tectonics. It also discusses protoliths, foliation, migmatites, contact metamorphism, and regional metamorphism.
Carving the Landscape
Water: Erosion and Deposition - Questions
The episode discusses how rivers play a vital role in the sculpting of land. It shows landscapes formed by rivers, the various types of rivers, the basic parts of a river, and how the characteristics of rivers — their slope, channel, and discharge — erode and build the surrounding terrain. The episode also covers river bars, meanders, cut banks, aspects of flooding including floodplains, and the evolution of rivers.
Water: Landscape Evolution - Questions
The episode explains how rivers carve such features in the landscape as canyons, discussing erosion and deposition processes as they relate to river characteristics and type of rock. It also discusses base levels, peneplains, stream terraces, incised meanders, river deltas, stream rejuvenation, the evolution of rivers, and efforts to prevent consequences of river flow that are harmful to humans, such as flood control efforts on the Mississippi River.
The episode focuses on how most fresh water comes from underground, making groundwater an important natural resource. It discusses aquifers and aquicludes; rock porosity and permeability; effluence; artesian wells; the water table; the formation of caves, stalactites, and stalagmites; sinkholes; ways in which groundwater can become contaminated; how groundwater is recharged naturally; and the role of hydrogeology in groundwater management.
Dust and Deserts - Questions
The episode shows how deserts are defined by infrequent precipitation, where most deserts are located, and how desertification relates to proximity to the equator, proximity to mountains, and ultimately plate tectonics. It describes alluvial fans, interior drainage patterns of deserts, desert pavement, and desert varnish; examines how wind transports sand and creates dunes, dry lakes, blowouts, and oases; and addresses efforts to reduce desertification.
The episode discusses how glaciers shape the landscape, explaining the formation, structure, and movement of glaciers and how they gouge and accumulate earth and rocks. It also describes basal slip, the snow line, glacial striations, till, glacial landforms such as moraines, and how the study of glaciers may help us understand ice ages and the greenhouse effect.
Beaches and Coasts - Questions
The episode discusses the dynamic interaction of rocky landmasses and the energy of the ocean, describing the types, parts, sources of energy, movement, and impact on the shore of waves. It also covers shoreline characteristics, refraction, currents, sea barriers, tides, tsunamis, how dams affect beach erosion, how the greenhouse effect could affect sea level and coastal lands, and the role of geologists in protecting the coastline.
Living With Earth
With Earth: The Loma Prieta Earthquake - Questions
The episode uses the 1989 Loma Prieta earthquake in California as the starting point for a discussion of how humans are learning to cope with earthquakes, methods of studying earthquakes, and how various groups and agencies are studying the San Andreas Fault and the damage caused along its path during the Loma Prieta earthquake to better understand how earthquakes affect the land, buildings, and people. It also discusses aftershocks, liquefaction, scientific concerns about the Hayward Fault, the cause of most human casualties during earthquakes, and what can be done to limit casualties and property damage in the event of an earthquake.
With Earth: Preserving the Legacy - Questions
The episode discusses the impact on the Earth of the Industrial Revolution, as well as where petroleum comes from, how it is discovered and extracted, and how it is converted into energy, and the effects on the Earth of oil drilling and the burning of fossil fuels. It also examines the potential of alternative energy sources, including the pros and cons of, and problems related to, the exploitation of geothermal energy.
|The Habitable Planet: A Systems
Approach to Environmental Science is a course for high
school teachers and undergraduate students in
environmental science. The content course will help
teachers of biology, chemistry, and Earth science to
provide more content in their classes. The course
components include 13 half-hour video programs, a
coordinated website which includes the streamed video
programs, the course text online, five interactive
simulations, background on the scientists who created
the content and those whose research is documented, a
professional development guide, and additional
Planets, One Earth - Questions
Astronomers have discovered dozens of planets orbiting other stars, and space probes have explored many parts of our solar system, but so far scientists have only discovered one place in the universe where conditions are suitable for complex life forms: Earth. The early Earth was a much different planet than the one we know today. Ancient rocks provide evidence of the emergence of oxygen in the atmosphere and of a frozen Snowball Earth. Scientists Paul Hoffman and Andrew Knoll look at these clues to help explain the rise of complex animal life.
The atmosphere is what makes the Earth habitable. Heat-trapping gases allow ecosystems to flourish. While the NOAA Global Monitoring Project documents the fluctuations in greenhouse gases worldwide, MIT's Kerry Emanuel looks at the role of hurricanes in regulating global climate.
Oceans cover three-quarters of the Earth's surface, but many parts of the deep oceans have yet to be explored. Learn about the large-scale ocean circulation patterns that help to regulate temperatures and weather patterns on land, and the microscopic marine organisms that form the base of marine food webs. Ocean systems operate on a range of scales, from massive systems such as El Niño that affects weather across the globe to tiny photosynthetic organisms near the ocean surface that take in large amounts of carbon dioxide. This program looks at how ocean systems regulate themselves and thus help maintain the planet's habitability.
Why are there so many living organisms on Earth, and so many different species? How do the characteristics of the nonliving environment, such as soil quality and water salinity, help determine which organisms thrive in particular areas? These questions are central to the study of ecosystems—communities of living organisms in particular places and the chemical and physical factors that influence them. Learn how scientists study ecosystems to predict how they may change over time and respond to human impacts. Scientists from the Smithsonian Center for Tropical Research document the astounding abundance of diversity in tropical rainforests to discover why so many species coexist that are competing for the same resources. In North America, the Yellowstone Wolf Reintroduction project explores why removing just one species dramatically changed the distribution of plants and animals up and down the food web.
Population Dynamics - Questions
What factors influence human population growth trends most strongly, and how does population growth or decline impact the environment? Does urbanization threaten our quality of life or offer a pathway to better living conditions? What are the social implications of an aging world population? Discover how demographers approach these questions through the study of human population dynamics. The human population of our planet now exceeds 6.5 billion and is rising. Much of this growth is projected for the most environmentally fragile regions of the world. Will studying the history of the world's population growth help predict the Earth's "carrying capacity"?
Exposure, and Health - Questions
We are exposed to numerous chemicals every day from environmental sources such as air and water pollution, pesticides, cleaning products, and food additives. Some of these chemicals are threats to human health, but tracing exposures and determining what levels of risk they pose is a painstaking process. How do harmful substances enter the body, and how do they damage cells? Learn how dangers are assessed, what kind of regulations we use to reduce exposures, and how we manage associated human health risks. We all require food, air, and water to survive—which are contaminated to some extent by man-made pollutants. Two studies, one in a rural western mining town and another in a dense urban population, reveal how these exposures impact health, and what can be done to reduce the risks.
Demographers project that Earth's population will peak during the 21st century at approximately ten billion people. But the amount of new cultivable land that can be brought under production is limited. In many nations, the need to feed a growing population is spurring an intensification of agriculture—finding ways to grow higher yields of food, fuel, and fiber from a given amount of land, water, and labor. This unit describes the physical and environmental factors that limit crop growth and discusses ways of minimizing agriculture's extensive environmental impacts. Will world population outrun food resources? The "Green Revolution" of the 20th century multiplied crop yields, in part through increasing inputs of pesticides and fertilizers. How can farmers reduce their use of agricultural chemicals and still produce enough food?
Resources - Questions
Earth's water resources, including rivers, lakes, oceans, and underground aquifers, are under stress in many regions. Humans need water for drinking, sanitation, agriculture, and industry; and contaminated water can spread illnesses and disease vectors, so clean water is both an environmental and a public health issue. In this unit, learn how water is distributed around the globe; how it cycles among the oceans, atmosphere, and land; and how human activities are affecting our finite supply of usable water. While essential to the lives of humans and animals, fresh water only accounts for six percent of the world's water supply. Scientists in Florida's Everglades and the water challenged Southwest consider the optimum use of existing sources of fresh water for both humans and ecosystems.
Decline - Questions
Living species on Earth may number anywhere from 5 million to 50 million or more. Although we have yet to identify and describe most of these life forms, we know that many are endangered today by development, pollution, over-harvesting, and other threats. Earth has experienced mass extinctions in the past due to natural causes, but the factors reducing biodiversity today increasingly stem from human activities. In this unit we see how scientists measure biodiversity, how it benefits our species, and what trends might cause Earth's next mass extinction. Species are being lost at a rapid rate in rainforests and coral reefs. Yet many species still have not been discovered. Tropical scientists struggle to keep ahead of the bulldozers as they work to understand this complex ecosystem. And an ocean biologist predicts the death of life and the "rise of slime" in the sea. How can we protect the biodiversity of these vulnerable ecosystems?
Challenges - Questions
Global energy use increases by the day. Polluting the atmosphere with ever more carbon dioxide is not a viable solution for our future energy needs. Can new technologies such as carbon sequestration and ethanol production help provide the energy we need without pushing the concentrations of CO2 to dangerous levels? Industrialized nations rely on vast quantities of readily available energy to power their economies and produce goods and services. As populations increase in developing countries and citizens demand better standards of living, global energy consumption will continue to rise, along with demands for non-fuel mineral resources such as iron and steel. Learn about new technologies that can produce ample supplies of energy without some of the environmental costs linked to current energy resources.
Pollution - Questions
Many forms of atmospheric pollution affect human health and the environment at levels from local to global. These contaminants are emitted from diverse sources, and some of them react together to form new compounds in the air. Industrialized nations have made important progress toward controlling some pollutants in recent decades, but air quality is much worse in many developing countries, and global circulation patterns can transport some types of pollution rapidly around the world. In this unit, discover the basic chemistry of atmospheric pollution and learn which human activities have the greatest impacts on air quality. Once released, air pollutants react chemically with each other under solar radiation to become even more dangerous secondary pollutants. A company in the Northeast U.S. tracks the emission of pollutants at street level, while an international long-term study follows plumes of pollution from Mexico City across the continent and beyond
Changing Climate - Questions
Earth's climate is a sensitive system that is subject to dramatic shifts over varying time scales. Today human activities are altering the climate system by increasing concentrations of heat-trapping greenhouse gases in the atmosphere, which raises global temperatures. In this unit, examine the science behind global climate change and explore its potential impacts on natural ecosystems and human societies. Tropical glaciers are the world's thermometers; their melting is a signal that human activities are warming the planet. A California project tries to predict whether natural ecosystems will be able to absorb enough additional carbon dioxide from the atmosphere in the next 50 years to mitigate the full impact of human-induced greenhouse gas emissions.
Forward: Our Global Experiment - Questions
Emerging technologies offer potential solutions to environmental problems. Over the long-term, human ingenuity may ensure the survival not only of our own species but of the complex ecosystems that enhance the quality of human life. In this unit, examine the wide range of efforts now underway to mitigate the worst effects of man-made environmental change, looking toward those that will have a positive impact on the future of our habitable planet. Earth's essential systems are being stressed in many ways. There are many tipping points in the environment, beyond which there could be serious consequences. Will human ingenuity, resiliency, and cooperation save us from the worst outcomes of our global experiment?
|Produced by the
Harvard-Smithsonian Center for Astrophysics. 2006.