 Coastlineso Emergent coasts- Uplifted, tectonically active coasts often rocky- Land uplifts/sea level drops- Rocky headlands alternate with pocket beaches formed by wave erosiono Erosion coastal features- Wave cut platforms  Breaking waves + pebbles/boulders/etc. = erosion Abrasion across surf zone erodes bedrock flat - common feature on rocky coasts- Sea stacks  Remnants of erosion Arch has collapsed- Sea arches  Remnants of erosion- Uplifted beach terraces  Can be either wave cut platforms or beaches or both Common on emergent coastso Submergent coasts- Land drops/sea level rise- Estuary : drowned river valley- Tied Island : island connected to mainland by tombolo- Fjord : drowned glacier valley Tideso Ocean tides are the result of the gravitational attraction of the moon and sun on the ocean- Causes the water to bulge outward on the side nearest to the moon- On the opposite side, inertia created by Earth’s rotation causes ocean water to bulge outward in the opposite direction- 2 oceanic bulges so 2 sets of tides daily- When a location lies under a bulge, it experiences a high tide & when a location passes under a depression, it feels a low tide Extra low tides (Neap Tide)o Sun and Moon are at right angles (quarter moon) – extra low high tides Extra high tides (Spring Tide)o Sun and Moon are in line with each other- Number of factors influence the timing and reach of tides: Sun’s gravity - Sun’s attraction counteracts the Moon’s gravity The difference between high and low tide varies in different parts of the ocean depending on how much space the water has to go into. Coastal Erosiono Preventing beach erosion- Structural approaches (e.g. groins, breakwater, jetties): typically cause increased erosion down-current of structure Groins: catch part of the “river of sand” from longshore drift Breakwater : reduces local wave energy so sand is deposited, not carried away Seawall and riprap Sand bagging : does not work Jetties : basically a groin placed at the mouth of a river- Non-structural approaches (e.g. beach nourishment, land use planning): expensive, but doesn’t cause erosion in new areas beaches can be replenished by pumping in sand; usually it doesn’t last more than a few years Miami Beach = one of the few success