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Lesson 16: Coastal Dynamics Geological Oceanography. The Earth’s coasts. There are two main ways to classify coasts: 1) based on location and 2) based on coastal formation Coasts are constantly changing as a result of natural processes Human activities also modify the coasts.
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Lesson 16: Coastal Dynamics Geological Oceanography
The Earth’s coasts • There are two main ways to classify coasts: 1) based on location and 2) based on coastal formation • Coasts are constantly changing as a result of natural processes • Human activities also modify the coasts
Coasts can be classified based on geological location • Active coasts are close to plate boundaries where plate collisions result in volcanoes and earthquakes • Passive coasts are far away from plate boundaries and have little volcanic activity and earthquakes
Plate boundaries are shown in bright yellow Identify the active and passive coasts Is the Pacific coast active or passive? What about the Atlantic coast? Passive! It is far from a plate boundary Active! It is right near a plate boundary Photo: NOAA
Coasts can also be classified based on the way that they are formed
Two types of primary coasts Photo: USGS Deltas • Wide continental shelf • Accumulated sediment forms a triangular shape Volcanic coasts • Volcanoes build up on the sea floor, eventually breaking the surface and forming island chains Nile River Delta Photo: NOAA Hawaiian Islands
Two types of secondary coasts Photo: NASA Marine-deposition coast • Sea action causes sediment accumulation in one place forming mud flats, salt marshes, beaches and barrier islands Coasts built by organisms • Organisms build structures like coral reefs and mangroves Barrier Island, Mexico Photo: NASA Great Barrier Reef, AUS
Coasts are dynamic, constantly changing • What types of processes do you think might affect coasts? • Natural processes like wind, waves, currents and erosion move sediments and change primary and secondary coasts • Erosion refers to the breakdown and transport of sediment, sand, rock and other material by physical forces • Wind and waves can move sand and other sediment and can wear away rocks near the shore
How do human activities shape the coasts? • Human activities can impact coastal processes, as well • In today’s activity, we will explore the effects of a manmade navigation channel on a delta in Louisiana