Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS
SAF Archives  search ask the scientists in the classroom cool science


Guide Index

Under and Around the Red Sea

Tomb of the Pyramid Builders

Science and the Brain

Oasis of the Ancestors

Saving Storks in the Sinai

Ancient Flutes in Egypt
in the classroom
TEACHING GUIDES


SHOW 304: Under and Around the Red Sea


The Red Sea, site of an ancient "miracle," is today a popular tourist attraction. Its shallow-water coral reefs lure snorklers and divers but their sport endangers the fragile ecosystem. FRONTIERS examines Professor Hudi Benayahu's practical idea for salvaging natural reefs: grow new ones. On a more theoretical front, we meet oceanographer Doron Nof, who believes he can explain scientifically how the Red Sea waters might have parted for the fleeing Israelites, as recounted in the Old Testament.

Activity 1: Understanding Coral Dynamics
Activity 2: Create Your Own Earthquake



ACTIVITY 1: UNDERSTANDING CORAL DYNAMICS

MEASURE, INTERPOLATE, ESTIMATE

Try these math problems to get a better understanding of coral:

  • From a local pet store, pick out a few pieces of coral. Measure the interpose distance (number of millimeters from one hole to the next). Based on a small sample area, perhaps one square centimeter or an even smaller area of 25 square millimeters (5mm x 5mm), estimate how many holes would be present in the entire sample. Record the interpose distance of the other types of coral. Calculate their mean (average value). Are they different from the first coral?

  • Coral can't live in water cooler than 18 degrees C. Using F = 9/5 C + 32, find the temperature in Fahrenheit.

  • Coral polyps are less than one inch in diameter. Find the equivalents in cm, mm, m. Coral polyps can be more than a foot in length; how big is that in cm, mm, m?


ONLY 500 MILLION YEARS OLD: CORAL POLYPS

Imagine you are an alga destined to nourish a polyp, a mere singular unit of a coral reef:
  • Describe the journey from ocean freedom to cellular confinement within this organism.

  • Create an anatomy and physiology comparison chart of each component of this invertebrate and that of its algae diet; for example, the green brain coral derives its emerald hue from algal zooxanthellae (dinoflagellates).

  • Cartoon the symbiosis of this happy couple: algae yields nutrients for coral to construct reef efficiently, and coral yields anchorage location in shallow water so sunlight can drench algae to undergo photosynthesis.




ACTIVITY 2: CREATE YOUR OWN EARTHQUAKE

... AND THE WALLS CAME TUMBLIN' DOWN

As you see on FRONTIERS, oceanographer Doron Nof theorizes that a combination of strong winds and a land ridge in the Red Sea could explain the "miracle" of the Exodus. Scientists are turning to Biblical accounts for more clues to history and archaeology of ancient times. Stanford University geophysicist Amos Nur has tracked earthquakes noted in the Old Testament; from the way the columns fell, he theorizes that a quake probably brought down the walls of Jericho.

The region under and around the Red Sea is now and has been geoactive for millions of year. In September 1992, an earthquake occurred in Egypt along a section of the East African Rift, part of a larger rift system that runs from Turkey through Israel, down the Red Sea, across Africa and into Uganda. The rift is causing Africa, the Middle East and Europe to spread apart at a rate of about one inch a year.

TRY IT!
  • You can simulate the effects of earthquake vibrations -- Primary (P), Secondary (S) and Long (L) waves. Cover a work area with several layers of newspaper. Make mini-bricks from clay by flattening the clay to about 1 cm thick and cutting a few hundred small rectangles to make scale-model bricks. Cover the bricks with a layer of waxed paper, then a pieces of half-meter square, half-inch plywood to keep them from curling. When they are thoroughly dry (this will take several days), remove the bricks, then clamp the plywood firmly to a table top, allowing an overhang of 10 to 15 cm.

  • Make buildings, walls and turrets on top of the plywood. Test the structures to see if they could survive a simulated earthquake. Strike the edge of the plywood with a hammer to simulate P waves. Simulate S waves by striking down or up on the overhanging edge. Strike the plywood with two hammers, once as you did to create the P wave and at the same time on the overhang 90 degrees to the right or left to simulate L waves. Create the three waves rapidly in order.

  • The harder you strike the wood, the more intense the "earthquake." How does your simulated earthquake affect different structures? What would happen if the bricks were glued or cemented with clay? Document the event by taking pictures before, during and after the experiment and then recount the story.






 

Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.