Friday, May 9, 2008
Day Four, May 8, 2008
Students Hana Mardis from the Kansas School for the Deaf and Heather Nurse from Iowa School for the Deaf contributed to today’s blog.
Beach Geology Day
We arrived at Laguna Beach on a cloudy cool day to look around the tidal pools in the rocks by the ocean. We were joined today by Will Snyder, an education researcher who is interested in how the Faults in the Field trips have been set up as a learning experience. Inside small depressions in the rocks, there were natural mini-aquariums full of sea life. We saw crabs, starfish, chitons, and some sea anemones in the tiny pools. Out in the ocean we sighted some dolphins swimming past, and some pelicans landing on a rocky outcropping just off the shore.
After exploring the seashore life, Laura Dair,a graduate student at University of Massachusetts, and Dr. Cooke showed the group of example of liquefaction, stepping into the wet sand and watching how it pools with water, she said that the wet sand showed the same kind of liquid movement as the some places in the ground during an earthquake. Michelle explained that the experiments we did on fault formation in our classroom sandboxes demonstrate the way the real earth has moved at Laguna Beach. She explained to us about how water carries sediments, and that high energy water can move larger sediments, but low energy water carries small sediments. We found several examples of layers wil different size sediments.
San Onofre State Beach
Next stop, we visited San Onofre State Beach where we enjoyed a picnic lunch. After lunch Laura Dair drew a diagram and showed us how waves coming from the ocean cut a platform that helps contribute to the shaping of the land into stair steps after many many years. She showed in the diagram how the bottom layer of the cliff is older than any of the layers above it.
We then took a winding walk down the cliffs to the beach. All along the beach were large standing cliffs. At the end of the beach on the top of the cliff there were two large white domed buildings of a nuclear power plant. Drs. Cooke and Marshall explained about three earthquake hazards: ground rupture, ground shaking, and liquefaction. Earthquakes can trigger landslides and tsunamis. They told us about some of the history of the geologists who studied the land to see if it was safe for the location of the power plant. The geologists who studied the fault for the power company found that the fault on this beach is inactive and therefore stable enough to build the plant. The evidence they found was that there is over 125,000 years worth of sediments on top of the layers with the faults. This is evidence that the fault has not moved in all of that time and so it must be inactive. We stopped at several locations to look at faults clearly visible in the cliff face.
Blue Bird Canyon Landslide
The weather cleared in the afternoon to bright skies. We stopped at Blue Bird Canon to see a place in a residential neighborhood where a landslide had caused severe damage in 2005 in which three expensive homes were completely destroyed. The land that was destroyed by the landslide has been retrofitted with materials to protect it from the top or head of the landslide to the toe. The government has stabilized the area with drainages, reshaping, tree plantings and fabric on the surface and booms across it and fabric to protect the hill from erosion. No new houses will be allowed to be built on this site.
Aliso Creek Beach
The rest of the day and early evening we spent at Aliso Creek Beach. We took a walk and we searched some of the rocks along the base of the shoreline cliff. Drs. Cooke and Marshall drew the diagram from the hillside of a layer of mud and asked us to compare it to a layer of pebbles/boulders (called a conglomerate) and explain which one took more time to deposit. We divided up into two teams to discuss the question and then reported out our answers. Dr. Marshall said all the answers had merit, but the mud layer would definitely take much longer to build up. He explained how the the large sediments were laid down by landslides that happened under the ocean, where underwater rock slides can happen, when earthquakes cause rocks and pebbles to be slide down and build up a layers. During one single storm a layer several feet thick can be deposited. That means a large sediment layer can be made at a much faster rate than for the mud layer, which probably required thousands of years to slowly build up. He said that the cliff along the beach, would have been made under the ocean, and much later the land was pushed up by faulting and other geological processes.
After our last geology talk for the day, we all enjoyed a great evening on the beach with a hamburger and hot dog cook out, playing Frisbee, and running in and out of the water’s edge. On our way back we took a short ride on a ferry that only holds three cars across to the town of Balboa. It was our last day in the field with Dr. Cooke and all of the other geologists. What a great week this has been! Tomorrow we will create presentations to show what we have learned.
Beach Geology Day
We arrived at Laguna Beach on a cloudy cool day to look around the tidal pools in the rocks by the ocean. We were joined today by Will Snyder, an education researcher who is interested in how the Faults in the Field trips have been set up as a learning experience. Inside small depressions in the rocks, there were natural mini-aquariums full of sea life. We saw crabs, starfish, chitons, and some sea anemones in the tiny pools. Out in the ocean we sighted some dolphins swimming past, and some pelicans landing on a rocky outcropping just off the shore.
After exploring the seashore life, Laura Dair,a graduate student at University of Massachusetts, and Dr. Cooke showed the group of example of liquefaction, stepping into the wet sand and watching how it pools with water, she said that the wet sand showed the same kind of liquid movement as the some places in the ground during an earthquake. Michelle explained that the experiments we did on fault formation in our classroom sandboxes demonstrate the way the real earth has moved at Laguna Beach. She explained to us about how water carries sediments, and that high energy water can move larger sediments, but low energy water carries small sediments. We found several examples of layers wil different size sediments.
San Onofre State Beach
Next stop, we visited San Onofre State Beach where we enjoyed a picnic lunch. After lunch Laura Dair drew a diagram and showed us how waves coming from the ocean cut a platform that helps contribute to the shaping of the land into stair steps after many many years. She showed in the diagram how the bottom layer of the cliff is older than any of the layers above it.
We then took a winding walk down the cliffs to the beach. All along the beach were large standing cliffs. At the end of the beach on the top of the cliff there were two large white domed buildings of a nuclear power plant. Drs. Cooke and Marshall explained about three earthquake hazards: ground rupture, ground shaking, and liquefaction. Earthquakes can trigger landslides and tsunamis. They told us about some of the history of the geologists who studied the land to see if it was safe for the location of the power plant. The geologists who studied the fault for the power company found that the fault on this beach is inactive and therefore stable enough to build the plant. The evidence they found was that there is over 125,000 years worth of sediments on top of the layers with the faults. This is evidence that the fault has not moved in all of that time and so it must be inactive. We stopped at several locations to look at faults clearly visible in the cliff face.
Blue Bird Canyon Landslide
The weather cleared in the afternoon to bright skies. We stopped at Blue Bird Canon to see a place in a residential neighborhood where a landslide had caused severe damage in 2005 in which three expensive homes were completely destroyed. The land that was destroyed by the landslide has been retrofitted with materials to protect it from the top or head of the landslide to the toe. The government has stabilized the area with drainages, reshaping, tree plantings and fabric on the surface and booms across it and fabric to protect the hill from erosion. No new houses will be allowed to be built on this site.
Aliso Creek Beach
After our last geology talk for the day, we all enjoyed a great evening on the beach with a hamburger and hot dog cook out, playing Frisbee, and running in and out of the water’s edge. On our way back we took a short ride on a ferry that only holds three cars across to the town of Balboa. It was our last day in the field with Dr. Cooke and all of the other geologists. What a great week this has been! Tomorrow we will create presentations to show what we have learned.
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