INTERNAL FORCES The intense heat of Earth’s interior creates the internal forces that change the planet’s surface. Internal forces cause the plates of Earth’s crust to move very slowly – only approx. 1 inch each year. It is these plate movements that create earthquakes and volcanic eruptions.
The theory of plate tectonics views Earth’s crust as divided into more than a dozenrigid, slow-moving plates. The processes of plate tectonics usually take millions of yearsto cause major changes. The plates move like giant rafts cruising slowly over the uppermantle.
How much of Earth’s interior remains unexplored? Why can’t humans journey to the center of Earth? What doesEarth’s core produce of significance? And what may be happening to the core?
Identify the components of Earth, including composition & dimensions. Explain the revolutionary idea to access the core.Is it feasible? And explain the value of earthquakes in studying the core.
Explain the significance of the core’s heat in protecting life from the sun’s deadly radiation. What is happening toEarth’s magnetic shield? And describe the potential significance.
Indicators reveal that Earth is changing from the inside out. The planet may be on the verge of a magnetic reversal.Has this happened before? How often does it tend to occur? And when was the last time Earth’s magnetic fieldreversed? What can we expect when it reverses again?
Studies reveal that Earth’s magnetic field may be weakening. Explain the “nuclear reactor” theory. Which planet doscientists use as a case study for this change? What is the theory as to what happened to Mar’s core? Describe theimpact? Could this happen on Earth? What would be the impact?
EARTHQUAKESEarthquakes are sudden movements of the surface produced when the slowly accumulatedstrain along opposing sides of an active fault is suddenly released as the two sides aretorn apart.
Thousands of perceptible earthquakes occur each year worldwide, while nearly 95% ofthem occur around the rim of the Pacific and from southern Asia westward throughsouthern Europe. Major earthquakes have also occurred in North America and LatinAmerica. Thus, there are not any regions in the world immune from earthquakes.
Although earthquakes could occur virtually anywhere in the U.S., the greatest potential islocated in California, ….
…. site of the infamous San Andreas Fault. This fault line is the source of most of thestate’s major earthquakes.
An earthquake’s profile includes: it occurs with little or no warning; it can unleash a forcecomparable to a nuclear blast; usually lasts less than one minute, but can level a city andcost billions of dollars in damage; and the aftershocks can be as dangerous & deadly as theactual quake. Most will proclaim that the worst aspect of experiencing an earthquake isthe loss of equilibrium from the shaking ground.
Earthquakes are more deadly and costly today because of overpopulation. In studying aworld population density map, one finds a clear correlation between the dense populationareas and the global distribution of earthquake activity.
In the past decade, earthquake activity has increased. In the absence of vacatingearthquake-prone areas, humans are adapting by: * Avoiding building on unstable ground (fill) * Avoiding the construction of high, rigid structures (overpasses) * Building earthquake-resistant structures * “Disaster Day” contingencies * Further development of prediction techniques Unfortunately, these adaptations can cost millions of dollars to implement. Poor, developing areas prone to earthquakes invariably suffer the highest casualties.
VOLCANISMVolcanism is the second major category of tectonic activity. It involves the surface-wardmovement of liquid magma.
A volcano is a hill or mountain constructed by materials from the interior of the earththat have been ejected under pressure from a vent. At present, approx. 500 activevolcanoes are scattered throughout the world. Nearly 4/5 of the active volcanoes on landare located in the “Ring of Fire” around the circumference of the Pacific.
Volcanic eruptions and thesubsequent lava flows are one ofthe most dramatic sites providedby nature.
Volcanic eruptions destroy everything in its path, including physical features and man-made features. Entire towns and cities can be destroyed. The aftermath can resembleanother planet’s surface. But despite the initial destruction, a re-birth slowly evolves inthe stricken area. Also, the eruption can serve as a valuable pressure release of internalplanetary pressure. Hawaii’s Mt. Kilauea helped to form the Hawaiian islands and continuing volcanic activity is increasing the size of Hawaii. Volcanic eruptions can impact both regional and world climates, depending on the magnitude of the eruption.
THE AGRICULTURAL REVOLUTIONPrior to the Agricultural Revolution, humans lived in smaller, nomadic bands that relied onhunting and gathering for subsistence. Humans lived in this manner until approx. 10,000years ago.Identify some of the challenges confrontinghunters and gatherers in North America.
The hunting and gathering subsistence lifestyle was harsh and tenuous, lacking reliablefood surpluses. Because of this unreliable food situation, how would the lives of ourancestors been different from ours?The primary big-game animal hunted was the mammoth, the largest creature roaming North Americasince the Dinosaurs. Explain the strategy for successfully hunting these big and dangerous animals.
During this early period, humans were at the complete mercy of their physicalenvironment for survival.Describe early weapon technology. How did early hunters and gatherers utilize the entire mammoth?And, what were the dangers for these people after a successful kill?
From the evidence discovered and some educated speculation, describe what life may have been like forhunters and gatherers in North America.
According to Carl Sauer, as early as 14,000 years ago, where might the earliest &most primitive plant domestication occurred? A similar, but later, development may havetaken place in northwestern South America (independent invention). This served as theseed for the more recognized agricultural revolution.
The Agricultural Revolution began approx. 10,000 years ago. This planned cultivation ofseed plants was a more complex process, involving seed selection, sowing, watering andwell-timed harvesting. According to geographers, what two locations likely initiated the Agricultural Revolution? Explain what characteristics compromised the revolution? This hearth of the Agricultural Revolution became known as the Fertile Crescent.
The domestication of animals occurred simultaneously with the domesticationof plants. Explain how these animals were initially domesticated. Whatwere the three uses for these early-domesticated animals?
IMPACT OF THE AGRICULTURAL REVOLUTION•Food surpluses were produced for the first time•An urban revolution occurred in conjunction with the Agricultural Revolution•Social stratification developed (occupational specialties)•Conflict and competition between villages developed•The development of organized religions•The more rapid development of “new” tools & technologies•Life expectancies increased/infant mortality dropsThe early civilizations (states) that developed as a direct result of theAgricultural Revolution included Sumer, Babylon, and Egypt.
Despite the transformation andaccelerated development of humansocieties since the AgriculturalRevolution, small pockets of humangroups continue to live a lifestylecharacteristic of the pre-Agricultural Revolution era.
HOW DID HOLOCENE HUMANITY TRANSFORM the EARTH? 1. FARMING 2. ADMINISTRATION 3. URBANIZATION 4. INDUSTRIALIZATION 5. TRANSPORTATION & COMMUNICATION 6. POPULATION
FARMINGThe First Agricultural Revolution has been followed by two more. Entire regions of Earthhave been farmed and grazed. No human activity transforms as much of the Earth’ssurface as farming does.
Ranching, the large-scale grazingof animals, is especially hard onthe land, contributing todesertification.
ADMINISTRATION The world has been compartmentalized into more than 200 countries and other entities. The imprint of the modern state is complex.
URBANIZATION In a matter of centuries, urban dwellers, rather than villagers, have become the majority of the world population. Today, many cities house more people than entire countries. Nothing better symbolizes Holocene humanity as present-day great cities.
INDUSTRIALIZATIONEven in the context of the Holocene period, industrialization as we know it is a latedevelopment. The Industrial Revolution occurred little more than two centuries ago.From the great industrial complexes to the slag heaps at the mines, the impact ofindustrialization is etched in the landscape.
TRANSPORTATION & COMMUNICATIONAnother symbol of humanity’s imprint is the global network of infrastructurecrisscrossing Earth’s surface.
This infrastructure bears witness to modern civilization; not even a new glaciation coulderase all of this evidence.
POPULATIONOvershadowing everything else is the almost unimaginable expansion of the humanpopulation during the Holocene, especially in recent centuries. From 6 million thepopulation has grown to 6 billion, a thousand-fold increase.