geology- shorelines

How did submarine canyons form? (lecture)

The drift is then ceased by a headland or groynes made by man, the sediments are forced to deposit on continental shelf and slope. As they deposit, turbidity currents can be formed and so do submarine canyons.

How are winter beaches different from summer beaches? What is the cause of this difference? (video)

Winter: the sand is gone, larger wave size Summer: sand on the beach, smaller wave size The wave size affects how much sand is on the beach because larger waves take away sand

What is a beach? What are some of the parts of the beach?

an accumulation of sediment such as sand parts of the beach- berms: flat platforms beach face: wet sloping surface that extends from the berm to the shoreline

How is the beach like a river of sand?

because sand flows down the coast like how water would flow down a stream

What is a rip tide? How and why do they form? How do you get out of one?

concentrated movements of water that flow in the opposite direction of breaking waves ; they form to get out of one you have to swim parallel to the shore for a few tens of meters

Contrast emergent and submergent coasts.

emergent coast: raised above sea level as a result of rising land submergent coast: result from rising global sea level or subsiding land

What is a semidiurnal tidal pattern?

2 high tides and 2 low tides in approximately 24 hours

Identify at least one stabilization method and discuss how it works.

Beach nourishment: sand is pumped into a beach from some other area, temporarily replenishing the sediment supply

What are some of the potential impacts of building jetties, groins, or other human structures along the shoreline?

Seawalls, groins, jetties and other shoreline stabilization structures have had tremendous impacts on our nation's beaches. Shoreline structures are built to alter the effects of ocean waves, currents and sand movement. They are usually built to "protect" buildings that were built on a beach that is losing sand. Sometimes they are built to redirect rivers and streams. Other times they are constructed to shelter boats in calm water. In many cases, seawalls, jetties, breakwaters and groins have caused down-coast erosion problems with associated costs that have greatly exceeded the construction cost of the structure.

What is the difference between a shore, shoreline, coast and coastline?

Shore: area that extends between the lowest tide level & the highest elevation on land; shoreline: line that marks the contact between land & sea; coast: area extends inland from the shore as far as ocean-related features are found; coastline: marks the coast's seaward edge

What observable features would lead you to classify a coastal area as emergent

wave cut benches and sea cliffs

Why do waves approaching the shoreline often bend?

waves move toward the shore at an angle and when they reach the shallow water, they are bent and become parallel to the shore

How does a wave's speed, wavelength, and height change as it moves into shallow water and breaks

when a wave enters water that is shallower than the wave base, it slows down allowing waves farther from shore to catch up

What is the effect of wave refraction along an irregular coastline?

10. In deeper water offshore, incoming waves move at constant speed, but they slow down in shallower waters. As an incoming wave approaches the shoreline at an oblique angle, the part of the wave in shallower water will have a lower speed than the part in deeper water. These different speeds for different parts of the same wave cause the wave to refract (bend). In general, wave refraction rotates obliquely incoming waves toward parallelism with the coastline. Over time, headland erosion and deposition in protected bays and coves tend to even out irregularities, thus straightening the coastline.

Which features result from deposition? Which result from Erosion? Which features indicate a submergent coastline? Which features indicate a submergent coastline

Deposition: spit, baymouth bar, tombolo, barrier island Erosion: wave cut notches, wave cut benches, uplifted marine terrace, sea arch, sea stack submergent:

Be able to identify groins, jetties, breakwaters, seawalls

Groins: barrier built at a right angle to trap sand that is moving parallel to shore Jetties: acts as a dam against longshore current and beach drift depositing sand Breakwaters: goal is to blunt the force of incoming ocean waves, to protect boats Sea walls: designed to armor the coast & defend property from force of breaking waves

Discuss the factors that influence the height, length, and period of a wave and describe the motion of water within a wave

How fast the wind blows, for how long, and over what distance determine the height, wavelength, and period of the resulting waves motion of water: travels along a short path shaped like a circle

Describe the motion of waves in deep water. What is the significance of wave base?

It moves up and down and slightly forward and backward with each wave. When the wave base is at a depth = to 1/2 the wavelength, the motion diminishes to zero

What causes the longshore current? Describe how it develops and relate it to where it flows?

Longshore currents are generated when a "train" of waves reach the coastline and release bursts of energy. Longshore currents are affected by the velocity and angle of a wave. When a wave breaks at a more acute (steep) angle on a beach, encounters a steeper beach slope, or is very high, longshore currents increase in velocity. Conversely, a wider breaking angle, gentler beach slope, and lower wave height slows a longshore current's velocity. In either case, the water in a longshore current flows up onto the beach, and back into the ocean, as it moves in a "sheet" formation.

Describe the features typically created from sediment deposited by longshore transport processes: spit, baymouth bar, tombolo, barrier island

Spit: ridge of sand that projects from the land into the open water of a bay Baymouth bar: sandbar that completely crosses a bay, sealing it off Tombolo: ridge of sand that connects an island to the mainland Barrier island: coastal plains that are flat and gently slope seaward

Are estuaries associated with submergent or emergent coasts?

Submergent

Where does the sand on the beach go when the beach ends? (video)

The sand is drained into a submarine trench

Explain the cause of tides, their monthly cycles, and patterns.

Tides are caused by the gravitational pull on ocean water by the moon and the sun; Quarter moon- moon is pulling earths water at a right angle relative to the sun

Describe the features typically created by wave erosion: wave cut notches, wave cut benches, uplifted marine terrace, sea arch, sea stack.

Wave cut notches: Wave cut benches: uplifted marine terrace: sea arch: sea stack:

Explain how waves erode and how waves move sediment along the shore.

the strong impact of waves combined w/abrasion erodes material along the shoreline; waves move sediment in a zigzag pattern along a beach face