exam 4 Flashcards
Characteristics of a summertime beach
Light and heavy wave activity alternate seasonally at most beaches, so the characteristics of the beaches they produce change, too. For example, light wave activity produces a wide sandy berm and an overall steep beach face—a summertime beach—at the expense of the longshore bar. Long time span.
Winter Time Beach
Conversely, heavy wave activity produces a narrow rocky berm and an overall flattened beach face—a wintertime beach—and builds prominent longshore bars. A wide berm that takes several months to build can be destroyed in just a few hours by high-energy wintertime storm waves. Short time span.
Longshore Current
The zigzag movement of water along the shore is called a longshore current. Longshore currents have speeds up to 4 kilometers (2.5 miles) per hour. Speeds increase as beach slope increases, as the angle at which breakers arrive at the beach increases, as wave height increases, and as wave frequency increases.
Longshore Drift
is the movement of sediment in a zigzag fashion caused by the longshore current.
Headlands
Juts out from landmass
Sea Caves
Waves pound relentlessly at base, may form sea caves
Arches
As waves continue to pound headlands, the caves erode through the other side for openings
Cliffs
Undermining upper portions, eventually collapase to form wave cut cliff levels
Marine Terraces
Uplift of the wave cut bench creates a gently sloping marine terrace above sea level
Spit
A linear ridge of sediment that extends in the direction of longshore drift from land into the deeper water near the mouth of a bar
Bay-mouth bar
cuts off the bay from the open ocean (build up of sand usually less than 1 meter above average sea level)
Tombolo
Sand ridge that connects an island or a sea stack to the mainland, can also connect two adjacent islands
Barrier Island
Extremely long offshore deposits of sand that are parallel to the coast
Delta
Some rivers carry more sediment to the ocean than longshore currents can distribute. These rivers develop a delta deposit at their mouths
Emerging Shorelines
Shorelines that are rising above sea level.
Features: Marine terraces are flat platforms backed by cliffs.
Submerging Shorelines
Shorelines sinking below sea level
Features: Wave cut benches below sea level. Submerged dune topography and drowned river valleys along the present shoreline.
Isostatic Adjustment
Earths crust sinks under the accumulation of heavy loads of ice, vast piles of sediment, or outpourings of lava. Rises when heavy loads are removed. Caused by glacial ice
Eustatic changes in sea level: what causes it?
Changes in sea level that are experienced worldwide due to changes in seawater volume or ocean basin capacity. The formation or destruction of large inland lakes may case small eustatic changes, or changes in sea floor spreading rates.
Hard Stabilization Structures
Built to protect a coast form erosion or to prevent the movement of sand along a beach
Groin
built perpendicular to a coastline and are specifically designed to trap sand moving along the coast in longshore transport. Some serious erosional problems have developed because of attempts to stabilize sand on the beach through excessive use of groins
Jetties
protects harbor entrances from waves and only secondarily does it trap sand. They can cause more pronounced upcoast deposition and downcoast erosions that groins
Breakwater
built parallel to a shoreline, composed of rocky blocky material that is piled up a meter or so above sea level. They are designed to reduce wave energy, creating a protected area of quiet water inshore of the breakwater. (may destroy coastal structures)
Seawall
one of the most destructive types of hard stabilization, built parallel to the shore along the landward side of the berm. Armor the coastline and protect landward developments from ocean waves
What is the exclusive economic zone (EEZ) and how far does it extend?
(200 miles, 370 kilometers) - A coastal zone from shore and establishes coastal nation jurisdiction including mineral resources, fish stocks, and pollution.
Vertically Mixed Estuary:
Shallow, low volume, salinity at any point is uniform, it increases from head to the mouth.
Slightly stratified estuary
somewhat deeper, salinity increases from the head to the mouth at any depth as in a vertically mixed. however, two water layers can be identified. One is the less saline, less dense upper water from the river and the other is the more saline, more dense deeper water from ocean. Circulation develops, called estuarine circulation pattern
Highly stratified estuary
deep, upper layer salinity increases from the head to the mouth, reaching a value close to open ocean. Deep water layer is uniform salinity. Mixing at the interface of the upper water and lower water creates net movement.
Salt Wedge
a wedge of salt water intrudes from the ocean beneath the river water. Typically of deep high volume rivers. Horizontal salinity gradient.
Estuaries
Coastal bodies of water where freshwater from rivers meets and mixes with saltwater from the ocean.
Lagoons
Shallow coastal water bodies separated from the ocean by a barrier (sandbar, coral reef, or barrier island). (Laguna Madre)
Marginal seas:
Large, semi-enclosed bodies of saltwater adjacent to an ocean, partially isolated by landmasses or underwater features (e.g.,The Mediterranean Sea).
Salt Marshes
generally occur between about 30 and 65 degrees latitude and support a variety of salt-tolerant grasses and other low-lying plants that are termed halophytic
Mangrove Swamps
restricted to tropical regions (below 30 degrees latitude) and support various species of salt-tolerant mangrove trees, shrubs, and palms.
How can oil spills be clean?
Microorganisms such as bacteria and fungi naturally biodegrade oil, so they can be used to help clean oil spills—a method called bioremediation
What causes Minamata disease?
Mercury poisoning
DDT:
A synthetic pesticide developed in the 1940s, widely used to control mosquitoes and agricultural pests.
PCBs
are industrial chemicals that were once widely used as liquid coolants and insulation in industrial equipment such as power transformers, where they were released into the environment.
Plankton
Plankton are mostly small organisms that drift with ocean currents.
Ex: Phytoplankton (diatoms, dinoflagellates), Zooplankton (krill, jellyfish, copepods)
Nekton
strong swimmers that can move freely.
Ex: Fish (tuna, sharks), marine mammals (dolphins, whales), squid
Benthos
live on the ocean floor, either attached, buried, or moving along the bottom.
Ex: Crabs, sea stars, corals, clams, sponges
DSL (deep scattering layer)
The Deep Scattering Layer (DSL) is a dense layer of marine organisms, mainly small fish, squid, and zooplankton, that migrate vertically in the ocean. It was first discovered using sonar, as it reflects sound waves, making it look like a “false” ocean bottom.
Adaptations:
Osmosis
Gills
Large eyes due to water transparency
Camouflage
What is the difference between pelagic environment vs. benthic environment?
The pelagic environment is the water column, while the benthic environment is the seafloor.
Pelagic organisms (nekton and plankton) swim or drift, while benthic organisms live on or within the seabed
Rip currents. What do they look like and what causes them to form?
The backwash from breaking waves usually returns to the open ocean as a flow of water across the ocean bottom, so it is commonly referred to as “sheet flow.” Some of this water, however, can return to the ocean in strong, narrow surface currents called rip currents that flow away from shore and are generally oriented perpendicular to the beach.
Rip currents are between 15 and 45 meters (15 and 150 feet) wide and can attain velocities of 7 to 8 kilometers (4 to 5 miles) per hour.
