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The Beach, A River of Sand

The Beach, A River of Sand. River of Sand Video. Berm: the nearly horizontal portion of the beach on the backshore formed by the deposition of sand. Where does sand come from?. From where do beaches come?.

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The Beach, A River of Sand

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  1. The Beach, A River of Sand River of Sand Video

  2. Berm: the nearly horizontal portion of the beach on the backshore formed by the deposition of sand

  3. Where does sand come from?

  4. From where do beaches come? • Sand, along with gravel, silt and clay are collectively known as sediment, and are produced by the mechanical and chemical breakdown of rocks. • Once disaggregated from the original source rock, this material is then eroded and transported by either wind, water, or ice, often ending up at the deposits of rivers or lakes, as sand dunes, or ultimately as sediment in the sea.

  5. What about when there are no mountains? • In areas where there is no good source of sedimentary material from mountains or volcanoes, sand is often entirely composed of organic material i.e. shell fragments, coral, and the tests (skeletons) of small planktonic organisms. The sand is said to be “biogenic.”

  6. Sand deposition

  7. La Jolla, California Summer Beach Gentle waves pile sand on the beach

  8. La Jolla, California Winter Beach Strong waves carry sand off the beach depositing it temporarily on off-shore sand bars

  9. The shape of the beach is determined by how it formed… • Why is it better to surf in the winter?

  10. it is all about sand movement

  11. Sand created features

  12. Longshore Drift consists of the transportation of sediment along a coast at an angle to the shoreline. It is dependent on 1. direction of the prevailing wind 2. swash (turbulent water that washes up on the beach) 3. backwash (offshore flow of water)

  13. Natural Sand Deposition Features

  14. What’s happening to Block Island?

  15. a local tombolo

  16. a local spit

  17. Local barrier beaches on south shore

  18. Some features are directly created by man

  19. Rip Currents • Bands of fast moving water moving off shore • Look for a channel of choppy water with a noticeable color difference

  20. DRAMATIC SEDIMENT FEATURES

  21. Sea Arch

  22. Sea Stack

  23. Blow Hole blow hole Hawaii

  24. Common constituents of sand: • Minerals: • Quartz : clear (doesn’t break down easily) • Feldspar : pinkish-tan • Mica: black and flaky • Olivine : olive • Hornblende : black/grey, dull • Garnet: reddish • Biogenic: • Coral • Shells • Foraminifera • Coralline algae • Rock: • Volcanic basalt (black islandic rock) • Granite

  25. How oceanographers analyze sand… • Color  composition • Rounding  distance traveled or age • Size  strength of waves, wind, glacier • Pits  directly from volcano • Sorting  distance traveled, # of sources of material

  26. … so scientists also know about the beach’s location by… • it’s steepness (from size) • what the parent material is (color) • distance the sand traveled to get there • the power of the beach’s waves (shape) • biogenic material…continental or island, tropical, temperate or polar • The influence of man (?)

  27. Wentworth sediment size scale, and resultant beach shape, for example

  28. What can you tell?

  29. Beaches are important habitats Headlands – Point Reyes, California Look!

  30. Elephant Seals

  31. “Haul Out” to molt

  32. beachmaster battle

  33. FUN with sand!!

  34. THE END

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