The Restless Ocean

WARM UP 11/3/14 The Gulf stream is a warm ocean current, it flows toward _________. What causes the deflection (bending) of ocean currents? Weathering _______ when surface area increases.

Beaches and Shoreline Processes Beaches are composed of whatever material is available Some beaches have a significant biological component Material does not stay in one place

Wave forces

Wave Forces

Wave forces Along the shoreline, waves are constantly: Eroding – breaking stuff down Transporting – moving it Depositing – putting it down somewhere

How? Wave impact: Waves hitting the shoreline creates a lot of erosion!

How else? Abrasion: sawing/grinding of rock fragments in water

Beaches and Shoreline Processes Wave refraction Bending of a wave Wave arrives more parallel to shore Results of wave refraction Wave energy is concentrated against the sides and ends of the headland Wave erosion straightens an irregular shoreline

Wave Refraction Along an Irregular Coastline Most of the energy from waves is here WEAK energy! Figure 10.12

Beaches and Shoreline Processes Longshore transport Beach drift—Sediment moves in a zigzag pattern along the beach face Longshore current Flows parallel to the shore Moves substantially more sediment than beach drift

Beach Drift and Longshore Currents END here START here Figure 10.13

Shoreline Features Erosional features Wave-cut cliff Wave-cut platform Cutting action of surf against the base of coastal land Wave-cut platform Left behind by a receding cliff Sea arch Next slide Sea stack Next next slide

Sea Arch – happens at the headland (when two caves unite) Figure 10.18

Sea Stack – an isolated remnant of a sea arch

Shoreline Features Depositional features Spit —A ridge of sand extending from the land into the mouth of an adjacent bay with an end that often hooks landward Baymouth bar —A sand bar that completely crosses a bay Tombolo—A ridge of sand that connects an island to the mainland

Aerial View of a Spit and Baymouth Bar Along the Massachusetts Coastline Figure 10.16

Spit Figure 10.18

Baymouth Bar

Tombolo Figure 10.18

Shoreline Features One more depositional feature! Barrier islands Parallel to the coast

What is this? Where is this?

Stabilizing the Shore Responses to erosion problems Building structures Types of structures Groins —Barriers built at a right angle to the beach that are designed to trap sand Breakwaters—Barriers built offshore and parallel to the coast to protect boats from breaking waves Seawalls – walls along the coast to absorb the impact of waves

Bird’s eye view of a groin

In Hilo, HI….

Stabilizing the Shore Responses to erosion problems Alternatives Beach nourishment by adding sand to the beach system

Miami Beach Before Beach Nourishment Figure 10.22

Miami Beach After Beach Nourishment Figure 10.22

Let’s see what you got out of this!

Waves do what along a shoreline? Erode Transport Deposit All of the above Answer: 4

What is an isolated remnant of a sea arch? Sea Stack!

The cutting and grinding of rock in water is called: Wave impact Abrasion Refraction Grindaction Answer: 2

Longshore currents move in what direction in relation to the shore? Diagonal Parallel In all directions Answer: 2

If energy is low, would you have deposition or erosion?

If energy is high, would you have erosion or deposition?

What is an example of an erosional feature? Wave-cut cliffs Platforms Sea Arches Sea Stacks

What is an example of a depositional feature? Spits Baymouth bar Tombolo Barrier Island

What are some ways of protecting the shoreline from erosion? Groins Breakwaters Seawalls

What is another way of protecting the coastline from erosion? Beach Nourishment

So how did ya do? Out of 10!

Compare and Contrast Feature Caused by erosion Caused by deposition Formed by fast moving waves formed by slow moving waves Picture Sea arch Spit Baymouth bar Tombolo Wave-cut cliff Sea stack Barrier islands

Study Guide questions you should be able to answer 2,3,8,10-14, 16, 18, 18, 22-32, 34,35,39 Omit #6