The Sea Flashcards
What does the size of a wave depend on
The wind and the fetch
Explain swash
The frothy water that rushes onto the shore after a wave breaks
Explain backwash
The water that runs back out to sea from the shore
Give the characteristics of a destructive wave
They have a lot of energy and have a strong backwash and weak swash. They erode the coastline
Give the characteristics of a constructive wave
They have a strong swash and a weak back wash. It deposits material and builds up the coastline.
Explain hydraulic action
The force of the water hitting the coastline causing it to erode
Explain air compression
The waves trap air in the cracks of rocks and as the waves retreat the trapped air expands and can crack the rock.
Explain abrasion
Eosin caused by the small rocks carried by the sea hitting against the coastline.
Explain attrition
Erosion caused by small rocks hitting each other and breaking themselves into smaller pieces.
Explain how a cliff is formed
The waves cut a notch in the rock creating an overhang. The notch then gets deeper and the overhang collapses leaving a wave cut platform. This continues and the coastline retreats inland.
Ex. Cliffs of moher. Co. Clare.
Explain how a bays and headlands are formed
A bay is a wide opening in the coastline and a headland is a pice of land jutting out to sea.
Soft rock erodes quickly and hard rock erodes slowly. A bay is formed when soft rock is eroded in between two pieces of hard rock and the headlands are the hard rock.,
Give and example of a bay and headland
Dublin bay and howth head
What is a sea cave and how is it formed
This is a tunnel at the base of a cliff but it doesn’t cut right through the cliff/headland.
The waves erode a weak point into the rock called a cave
Explain what and how a sea arch is formed
A sea arch is a passage that runs completely through a headland. T his can happen when a cave is eroded further or two caves meet in the middle to form a complete passage through a headland called a sea arch
Explain what and how a sea stack is formed
A sea stack is a pillar of rock standing I. The water near the coast.
When sea arches erode further a sea stack is formed. The roof of the arch collapse forming a pillar of rock isolated from the land.
When a sea stack is eroded what is left
A sea stump
What is a blowhole
A passage from a cave up to the surface of a cliff top
Explain how a blowhole is formed
Compressed air is trapped in the cave by strong waves
The pressure loosens the joints I. The rock above the cliff and eventually this falls into the cliff creating a passage known as a blowhole.
Give an example of a blowhole
The two pistols. Co. Donegal
What’s a rivers load and the seas load
River: sand, silt, clay
Sea: sand, pebbles, stones, and mud.
What two ways do waves transport material in The sea
- Up and down the shore. Swash and backwash
2. Long shore drift
Explain long shore drift
The movement of materials along the beach. The swash comes up the beach at an angle and the backwash comes back at another angle so the load is moved in a zigzag pattern.
Explain the fetch
The length that a wave has to travel
Explain a beach
This is built up of sand and shingle deposited by waves between low and high tide levels. Fine material is found on the lower beach and caorse material is found at the upper beach
Explain a storm beach
A beach that was created in a storm when material is hurtled up past normal high tide level
Give an example of a beach
Grey stones co. Wicklow, tramore Co.Wateroford
What are sand dunes and how they formed
Sand dunes are hills of sand that pile up on the shore beyond high tide level. Light dry sand is blown inland until trapped by wall or vegetation
Give an example of sand dunes
Rosslare co. Wexford, inch co. Kerry
Explain marram grass
Defence mechanism stops coast from eroding, bonds the sand together
What is a sand spit and explain how it is formed
A ridge of sand or shingle that is connected to the land at one end and extends into a bay. Material is moved by long shore drift. Material is deposited faster than eroded
Explain spit
Change in direction of the coastline
Give an example of a sand spit
Portmarnock co. Dublin
What is a lagoon and give examples
A lake of water cut off from the sea by a bank of sand or sand bar.
Ex. Lough Gill (Kerry), our lady’s island (Wexford)
What is a tombolo, how is it formed and give example.
A ridge of sand or shingle that joins an island to the mainland.
It’s formed when a sand spit grows outwards towards the sea and island and by long shore drift material is deposited between the island and mainland.
Ex. Howth, sutton
How do people try to control the destructive sea (three ways)
Sea wall
Boulders
Groynes
What are sea walls
Walls made from concrete with a curved top to help deflect the waves back out to sea.
What are boulders. In the context of the sea
Large rocks placed at the base of cliffs or I front of sand dunes to prevent erosion by reducing the waves power.
What are groynes
Lows wooden walls built at a right angle to the shore to help prevent sand from moving by long shore drift.
Explain a beach that you have studied.
It has: Beach Sea stack Cliffs Headlands Bay Sand spit Lagoon Sand dunes
Caravan sites, camp sites
Forts and castles.
