SCIENCE
Read more about mapping the seafloor with our profile of geologist Christina Symons.
Teachers, scroll down for a quick list of key resources in our Teachers’ Toolkit.
Map by EarthByte Group, School of Geosciences, University of Sydney, Sydney, NSW 2006, Australia National ICT Australia (NICTA), Australian Technology Park, Eveleigh, NSW 2015, Australia
Discussion Ideas
- Take a look at the legend for the spectacular new seafloor map. Rocks and minerals are labeled “siliciclastic,” “volcaniclastic,” “calcareous,” and biogenic “ooze.” What do these terms mean?
- A “clast” is simply a fragment of a rock. Clastic rocks are composed entirely of individual clasts, or bits and pieces of existing rocks and minerals. (It’s a handy geological word to know! Shows up everywhere from pyroclastic flows to clastic dikes.)
- Siliciclastic rocks are composed mostly of silicates, a type of mineral made of silicon and oxygen—and the most abundant types of rock on Earth. One of the most common seafloor silicates is quartz.
- Volcaniclastic rocks are just what they sound like—minerals made of the ash and lava that erupt with volcanoes.
- Calcareous rocks are made mostly of calcium carbonate—calcareous is a fancy word for “chalky.”
- Oozes are seafloor sediments that are at least 30% remains of microscopic creatures such as foraminiferans, radiolarians, or diatoms.
- Forams are fabulous little critters that excrete tiny “tests” of calcium carbonate. The blue-coded calcareous ooze identified in the new seafloor map is primarily composed of foram remains. Learn more about forams here.
- Radiolarians are tiny zooplankton that have equally tiny exoskeletons made of silicate. In addition to the green-coded radiolarian ooze, radiolarians also contribute to the siliceous part of the purple-coded “mixed calcareous-siliceous ooze” in the new seafloor map.
- Diatoms are phytoplankton that have a unique silicate cell wall. In addition to the lime-green-coded diatom ooze, diatoms also contribute to the siliceous part of the purple-coded “mixed calcareous-siliceous ooze” in the new seafloor map. Take a close-up look at a diatom here.
- A “clast” is simply a fragment of a rock. Clastic rocks are composed entirely of individual clasts, or bits and pieces of existing rocks and minerals. (It’s a handy geological word to know! Shows up everywhere from pyroclastic flows to clastic dikes.)
- How did scientists collect data for the dazzling new seafloor map?
- Scientists pored over results from about 14,500 sediment samples taken from the world’s ocean basins. Each little white dot on the new map corresponds to a sample site. This is a great example of “big data”!
Map by EarthByte Group, School of Geosciences, University of Sydney, Sydney, NSW 2006, Australia National ICT Australia (NICTA), Australian Technology Park, Eveleigh, NSW 2015, Australia
- What did NOT surprise scientists about the new seafloor map?
- Some seafloor sediments, such as volcaniclastic rocks around brand-new islands or coral deposits around huge coral reefs, were right where scientists thought they would be.
Map by EarthByte Group, School of Geosciences, University of Sydney, Sydney, NSW 2006, Australia National ICT Australia (NICTA), Australian Technology Park, Eveleigh, NSW 2015, Australia
- What DID surprise scientists about the new seafloor map?
- Take a look at the biogenically rich sediments surrounding Antarctica. According to the scientists who produced the map, “The new seafloor geology map demonstrates that diatom accumulations on the seafloor are nearly entirely independent of diatom blooms in surface waters in the Southern Ocean. ‘This disconnect demonstrates that we understand the carbon source, but not the sink,’ says one researcher. More research is needed to better understand the relationship between what goes on near the ocean surface and what is happening on the seafloor.”
TEACHERS TOOLKIT
EarthByte Group and the School of Geosciences, University of Sydney: Seabed Lithology interactive map
(extra credit!) Geology: Census of seafloor sediments in the world’s ocean
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