Tides, Shorelines, and Coral Reefs

Flashcards about Tides, Shorelines, and Coral Reefs

Tides

Rhythmic rise and fall of sea level, very long and regular shallow-water waves caused by gravitational attraction of the Sun, Moon, and Earth.

Lunar Tidal Bulges

Small horizontal forces push seawater into two bulges – One bulge faces the Moon, and the other bulge is on the opposite side of Earth.

High tide, flood tide

Seawater moves onshore

Low tide, ebb tide

Seawater moves offshore

Spring tide

Tidal range is greatest during new and full moons

Neap tide

Tidal range is least during quarter moons

Spring tide

Especially high and low tides with a large daily tidal range during new and full moons when gravitational forces are added together.

Neap tide

Daily tidal range is least because gravitational forces are offset during first and third quarters of the Moon

Declination

Impact tides because they shift lunar and solar bulges from the equator causing unequal tides.

Diurnal tidal pattern

Characterized by one high and low tide per day.

Semidiurnal tidal pattern

Two high and two low tides each tidal day, with little difference in the high and low water heights

Mixed tidal pattern

Two high and two low waters each day with large inequality in high water heights, low water heights, or both.

Tidal bore

Occurs when the leading edge of the incoming tide forms a standing wave of water that travels upstream, against the current of a river or narrow bay.

Flood current

Advances into the coastal zone.

Ebb current

Seaward moving water

Erosional Shorelines

Well-developed cliffs formed from recent tectonic activity

Depositional Shorelines

Primarily deposited by longshore drift

Barrier Island

Long, narrow offshore deposits parallel to shore, most developed due to rise of sea level about 18,000 years ago, common East and Gulf coasts of U.S., protect mainland from high wave activity

Emerging Shorelines

Shorelines above current sea level

Submerging Shorelines

Shoreline below current sea level

Global (eustatic) changes in sea level

Changes in sea floor spreading rates and ice volume changes.

Hard Beach Stabilization BMPs

Structures built to decrease coastal erosion and interfere with sand movement, often resulting in unwanted outcomes; some structures may increase wave erosion

Coral Reefs: Three Ingredients

CaCO3, Cementation, and sediment + nutrients

Fringing Reefs

Younger growths of reefs closer to shoreline

Barrier Reef

Older growths of reefs protecting the shoreline.

Atolls

Corals growing on top of volcano

Estuaries

Essential water quality filtering systems for the ocean; a coastal body of water surrounded by land where water levels rise and fall with the tide and salinity varies with the tide and rain.