Compression occurs in rocky areas when air enters into crack in rock. This air is trapped in cracks by the rising tide, as waves crash against the rock the air inside the crack is rapidly compressed and decompressed causing cracks to spread and pieces of rock to break off.
What causes cliffs erode?
Weathering happens when natural events, like wind or rain, break up pieces of rock. In coastal areas, strong winds and powerful waves break off soft or grainy rocks from hardier rocks. The harder rocks are left as cliffs.
Why do some cliffs erode quicker than others?
The fetch of the wave and the strength of the wind. Powerful winds and a long fetch create the most damaging (erosive) waves. The angle of the slope – steep slopes erode more violently and frequently. Weather conditions – freezing temperatures and heavy rain increase weathering and the rate of erosion.
Why do cliffs erode at different rates?
The wave assailing force is greatly controlled by water level, nearshore topography, and talus or ice cover at the cliff base. Fluctuations of these controlling factors produce temporal variations in erosion rates. The most important factor in dramatic erosion is an abnormal rise in water level, known as storm surges.
How fast do cliffs erode?
“We found erosion rates that vary from 17 millimeters per year to 118 millimeters per year at the different sites,” Huppert says. “The upper end of that range is nearly half a foot per year, so some of those rates are pretty fast for rock.”
Why do some cliffs collapse?
A wave-cut notch (small scale landform) is formed by erosional processes such as abrasion and hydraulic action , this is a dent in the cliff usually at the level of high tide. As the notch increases in size, the cliff becomes unstable and collapses, leading to the retreat of the cliff face.
What is the process of cliff erosion?
This often involves destructive waves wearing away the coast. There are five main processes which cause coastal erosion. These are corrasion, abrasion, hydraulic action, attrition and corrosion/solution. Corrasion is when waves pick up beach material (e.g. pebbles) and hurl them at the base of a cliff.
What causes erosion to occur more quickly?
Water. Water is the most common cause of soil erosion. When it rains for an extended period of time or floods, your ground gets so wet that it loosens and begins to flow with the water.
What would cause erosion to occur more quickly?
Remember, faster moving water causes erosion more quickly. Slower moving water erodes material more slowly. If water is moving slowly enough, the sediment being carried may settle out. This settling out, or dropping off, of sediment is deposition.
Why do some rocks erode more than others?
As erosion occurs, some rock is worn away quicker than some which allows for bays and headlands to be created. There are normally different bands of rock along a coastline, the weaker the rock, the quicker the erosion. More resistant rock is harder to erode so sticks out and leaves headlands.
What factors affect the rate of erosion?
Major factors that affect the amount of erosion are soil cloddiness, surface roughness, wind speed, soil moisture, field size, and vegetative cover. A discussion of each follows. The cloddiness of a given soil largely indicates whether the wind will erode it.
What type of weathering affects cliffs?
Chemical Weathering
The chemistry that makes up coastal rocks can be affected by rain and sea water leading to the gradual disintegration of solid rocks.
What mass movement affects cliffs?
Soil creep: the mass effect of individual particles taking a downwards trajectory over time from a cliff face as a result of wave-impact, rain splash, weathering and gravity.
What rocks erode fastest?
Soft rock like chalk will erode more quickly than hard rocks like granite. Vegetation can slow the impact of erosion. Plant roots adhere to soil and rock particles, preventing their transport during rainfall or wind events.
Where is erosion most rapid?
Typically, physical erosion proceeds fastest on steeply sloping surfaces, and rates may also be sensitive to some climatically-controlled properties including amounts of water supplied (e.g., by rain), storminess, wind speed, wave fetch, or atmospheric temperature (especially for some ice-related processes).
Do waves erode cliffs?
As waves attack the shore, headlands are eroded, producing steep sea cliffs. The waves vigorously attack the portion of the cliff near sea level where joints, fissures, and softer strata are especially vulnerable. The cliffs are undermined and caves are formed.
Why do cliffs slump?
Sub-aerial processes, such as rainfall, also cause erosion. This often happens where layers of boulder clay, left behind by melting glaciers, become saturated and cause the cliff to slump.
How do cliffs slump?
With rotational slumping, heavy rain is absorbed by unconsolidated material making up the cliff (often glacial till, or boulder clay). The cliff face becomes heavier and eventually it separates from the material behind at a rain-lubricated slip plane.
What stops cliffs from collapsing after heavy rain?
Rock bolting/pinning: this technique involves bolting unstable rock faces to increase cohesion and stability and prevent slippage, using metallic bolts, tie-rods, steel soil nails driven horizontally into the cliff. It reduces mass movements and thus reduces net erosion rates.
What happens when cliffs erode?
A wave-cut notch will be formed as the cliff is under cut by the erosive power of the waves, through the processes of hydraulic action, corrosion and corrasion. Eventually, the cliff becomes unsupported and collapses into the sea. The cliff retreats and leaves behind a wave-cut platform which is visible at low tide.
What are the effects of cliff collapse?
Landslides and coast cliff collapse can result in: Damage to or loss of land. Damage to or loss of buildings, vehicles or infrastructure. Injury to people or animals.