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Notes - Shorelines
The document discusses different types of depositional shorelines including bay barriers, tombolos, barrier islands, and spits. It also describes barrier islands in more detail, including their anatomy, migration over time, and comparison to deltas and emerging vs. submerging shorelines. Finally, it covers causes of changing sea levels from local tectonics and global mechanisms like glaciation and deglaciation that impact ocean levels.
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Notes - Shorelines
- 1. Depositional Shorelines Abay barrier, or bay mouth bar, seals off a lagoon from the ocean. A Tombolo is an sand bar that connects an island to the mainland. Barrier islands are long offshore sand deposits that parallel the coast. A spit connects at one end to the mainland and hooks into a bay at the other. © 2011 Pearson Education, Inc.
- 2. Depositional Shorelines © 2011 Pearson Education, Inc.
- 4. Depositional Shorelines Tombolo Barrier island © 2011 Pearson Education, Inc.
- 5. Barrier Islands Commonalong East and Gulf coasts of the United States Do not exist along erosional shorelines Protect mainland from high wave activity Can migrate landward over time © 2011 Pearson Education, Inc.
- 6. Ocean beach BarrierIsland Dunes Anatomy Barrier flat High salt marsh Low salt marsh Lagoon © 2011 Pearson Education, Inc.
- 7. Barrier Island OceanBeach – closest part of the island to the ocean Dune – stabilized by grasses; protect lagoon from strong storms Barrier flat – grassy area that forms behind dunes © 2011 Pearson Education, Inc.
- 8. Barrier Island Highand low salt marshes – biologically productive wetlands Generate peat deposits of decaying organic matter Lagoon – water between barrier island and mainland © 2011 Pearson Education, Inc.
- 9. Barrier Islands Migratelandward over time due to rising sea levels Older peat deposits found on ocean beach © 2011 Pearson Education, Inc.
- 10. Deltas Triangular depositsof sediment where rivers empty into oceans or seas Distributaries carry sediment to ocean © 2011 Pearson Education, Inc.
- 11. Emerging Shorelines Shorelines above current sea level Marine terraces – flat platforms backed by cliffs © 2011 Pearson Education, Inc.
- 12. Submerging Shorelines Shoreline below current sea level Features include Drowned beaches Submerged dune topography Drowned river valleys (estuaries) © 2011 Pearson Education, Inc.
- 13. Changing Sea Level Two major processes can change sea level: Local tectonic processes Global (eustatic) changes in sea level © 2011 Pearson Education, Inc.
- 14. Changing Sea Level 1. Local tectonic processes Example: the Pacific coast of the United States is currently being uplifted. Isostatic adjustments – rebound of Earth’s crust after removal of heavy loads or sinking with application of heavy loads Ice-loading from glaciers during ice ages © 2011 Pearson Education, Inc.
- 15. Changing Sea Level 2. Global (eustatic) changes in sea level Sea level changes worldwide due to Change in… a. amount of available sea water b. in ocean basin capacity © 2011 Pearson Education, Inc.
- 16. Eustatic Changes inSea Level Some Mechanisms Ice ages lock seawater up in ice (glaciation) – sea level goes down Ice melting after an ice age (deglaciation) – sea level rises © 2011 Pearson Education, Inc.
- 17. © 2011 PearsonEducation, Inc.
- 18. Pleistocene Epoch andToday From about 2 million to 10,000 years ago, a series of four ice ages affected Earth. Sea level was at least 120 meters (400 feet) below today’s sea level. If all remaining ice on Earth melted today, sea level would rise another 70 meters (230 feet). © 2011 Pearson Education, Inc.
- 19. Global Warming andChanging Sea Level Globally averaged temperatures – about 0.6 C (1.1 F) warmer over last 130 years Sea level rose 10-15 cm (4-10 in) over past 100 years As global warming continues, we will see a higher sea level. © 2011 Pearson Education, Inc.