GEOLOGY and EARTH SCIENCE

Introduces glaciers, fossils, rock formation
and erosion, geological structures, plate
tectonics, evolution, atmospherics, astron-
omy & space science. Very rich resource
material, some at OVER 50% DISCOUNT!

GEOTHERMAL ACTIVITY & ENERGY
Volcanoes and their power, geothermal activity world-wide and as a potential renewable energy resource. 3 programs. 1 video and 2 slide sets (40 slides), guides.
EP #309X SLI/VID
$129.95

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SAVE $35.00 ON 3 PROGRAM BUNDLE ORDER EP #309X.....$129.95
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A VISIT TO ST HELENS Video order #EV-2179V.................$79.95

The story of the famous eruption, the geologic history of the region, and the
devastation caused by the explosion and subsequent mud flows to such areas as Spirit
Lake and The Columbia River. Live action video.
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GEOTHERMAL ACTIVITY Slides order #309.............$42.50

Introduces geothermal activity, with special reference to Yellowstone Park. Also
presents hydrothermal activities in California, Iceland and New Zealand. The mechanisms
of hydrothermal activity are outlined and various typical features such as geysers, hot
springs, mud pots and fumaroles are illustrated. Also discusses potential for harnessing
this energy source. 2O slides and guide.

CONTENT SAMPLE: 21549 The most spectacular and awe inspiring form of
geothermal activity is a volcanic eruption. While they vary tremendously in magnitude, all are
overwhelming when viewed close up. The energy they contain and the forces activating them are
virtually incomprehensible.

A number of the most famous mountains in the world are volcanic in origin, including
Etna, Kilimanjaro, Fuji, Aconcagua and Lassen. In historic times there have been a number of
tremendous volcanic explosions that have completely wrecked existing volcanic cones, probably
the most famous of which was the eruption of Vesuvius in 79 A.D. that destroyed Pompeii. When
Krakatoa exploded in 1883 and Mt. Katami exploded in 1912, an estimated five cubic miles of
material was blown away in each case and millions of tons of dust were carried around the world
by air currents.

Every few years new volcanoes spring forth showering the surrounding area with cinders
and ash and often forcing the evacuation of nearby residents. In a matter of days or weeks a new
cone can be built up. Such was the case with this volcano, Surtsey, which developed just off the
coast of Iceland in the summer of 1966, eventually forcing the evacuation of a small fishing village.
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ENERGY PRODUCTION AT THE GEYSERS GEOTHERMAL RESOURCE
Slides order #324.............$42.50

Traces the history of this resource as an energy producer, details its current
generating capacity, and familiarizes the student with this alternative to fossil or nuclear
fuel for energy production. 2O slides and guide.

CONTENT SAMPLE: INTRODUCTION: Many areas of the world are now using
geothermal resources for heat or electrical power, or both. Until 1979, Larderello, Italy, was the
world’s largest producer of geothermal energy, as well as the first area to produce geothermal
electricity commercially, having begun in 1904. Wairakei, New Zealand, has also been producing
geothermal electrical energy commercially for many years. Mexico, Japan and Turkey produce a
modest amount of geothermal electricity, as does Hungary and Russia. Use of geothermal hot
water is age old, for hot water spas have been noted throughout history. Today, hot water for
heating dwellings is used in several countries, and in New Zealand it is also used for industry.
Central America is especially well-endowed with geothermal areas, but has made little use of
them to date.

The criteria for geothermal potential are temperatures of 59° to 200°C (150° to 400°F), an
economical drilling depth (now approximately 10,000 m or 33,000 ft.), sufficient rock permeability
to allow transfer of water or steam or both, and sufficient water recharge to allow long-term
operations.

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RELATED PROGRAMS WORTH NOTING
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COAL-FIRED GENERATING PLANTS--THEIR ECOLOGICAL IMPACTS Order #177.....$42.50

An analysis of the various impacts of a coal-fired electric generating plant.
Includes the effects on air and water, wildlife habitat, acid rain creation, and more. An
important topic given the renewed emphasis on coal as an energy source. 20 slides
and guide.

CONTENT SAMPLE: 21604 Electric generating plants can also cause thermal pollution.
Here on the Upper Mississippi River, we see two power plants which apparently have a common
cooling water intake at the far left and share a common water discharge gate to the right of the
intake. Foam from the discharge area traces the flow of heated water downstream.

In a modern generating plant, 40% of the coal's energy is converted to electric energy,
while the remaining 60% becomes waste heat. Some of this heat goes up the chimney, but the
rest must be removed to keep the generators working. Cold water sucked from rivers, lakes or
ocean has traditionally been used to absorb this waste heat. A large plant requires so much
water, as much as 500,000 gallons per minute, that it may use a good fraction of the entire flow
of a small river. The warm discharge water causes thermal pollution by raising the temperature
of the river.

Many organisms, particularly cold-blooded ones, are especially vulnerable to changes in
temperature. Moreover, as water temperature rises, the water holds less oxygen, so organisms
may die from oxygen starvation if not from the heat itself. Heat-loving organisms cannot become
established because the output of hot water varies, decreasing to nothing when the plant shuts
down.

Besides the problem of thermal pollution, there are also the harmful effects on fish and
other creatures that are sucked through the plant's cooling system. The sudden temperature
rise, action of the pumps or chlorine added to prevent clogging growths of microorganisms can all
be lethal. Screens are added to filter out the larger fish, but small organisms are still trapped
and killed.

To avoid damage to aquatic ecosystems, special cooling structures are often built for
power plants. These include cooling ponds, and wet and dry cooling towers. The latter have the
least impact on the environment, but unfortunately they are by far the most expensive. Waste
heat will be turned from problem to profit if several pioneering attempts to utilize hot water from
power plants are successful. For example, the heated water has been used to speed the growth
of cultured fish and to hasten the decomposition of sewage.

REVIEWS: "An excellent analysis of the environmental impact [of] the anticipated
switch from oil to coal...timely program is highly recommended." Previews. "...thorough...
examination of the costs and risks..." Media Review. "...cogent narration and incisive slides
provide an informative and balanced account." Booklist.
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THE GREENHOUSE EFFECT Slides order #SS-0975S........$37.50

Human activities such as fossil-fuel combustion, deforestation and emission of
particulate matter into the atmosphere may be shifting the delicate climatic balance that
poses our interglacial age between ice and flood. Change is inevitable, but in which
direction, and how fast? 15 frames and guide. (Filmstrip #SS-0975F........$15.00.)

CONTENT SAMPLE: 6. The atmosphere does not allow the long-wave radiations
emitted from the earth to escape directly into space. This is called the "greenhouse effect"
because it is analogous to heat retention in a greenhouse. The glass windows of a greenhouse
readily transmit the incoming solar radiation, but some of the re-radiated long-wave radiation
cannot escape through the glass. This infrared radiation is reflected by the glass walls back into
the greenhouse where it warms the air, soil and plants to temperatures that are higher than that of
the air outside. The same principle is being incorporated into the design of solar panels for
heating water or even entire buildings. Here the efficiency is enhanced by circulating warm air
through reservoirs of rocks or waters. These reservoirs serve to trap the re-radiated infrared
radiations, much as do the soil and ocean of the earth.
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~1875-026~ Volcanic activity. photo by Icelandic Tourist Bureau.

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