EROSION :
Erosion ( lat. erodere) means in the geoscientific sense the damage or creation of surfaceforms through abrasion of more or less weathered rocks.
Forms of Erosion:
1.) fluviatile erosion: through flowing waters forming for example V shaped valleys
Mosaic Canyon, Death Valley
Mojave-Wüste, Kalifornien, USA
2.) glacial erosion : through glaciers moving to the valleys slowly and forming U shaped valleys
Tyndall-Gletscher, Rocky Mountains, Montana, USA
3.) wind erosion: through air, if there dust and sand is moved there are greater effects
4.) marine erosion:
The transformation of the kinetic energy of waves when they reach mainland causes stone damage some metres around the sea level - in areas of greater tidal differences the region of influence is bigger.
So there are typical coastal phenomenons like caves or natural brigdes ( peninsula eroded from both sides) or sea stacks (Brandungspfeiler).
Coastal erosion occurs along beaches and shorelines. Both wind action and water action have important parts in this process and constantly change the boundary between land and water. Coastal erosion takes land away forever from one area to deposit it someplace else.
The beach is constantly pounded by waves which eventually break fragments of ground and rock into sand. How hard a beach is hit by waves depends on lunar tides and differences in water density.
There is no continuous groundcover on the beach, so sand dunes form easily. Wind blows sand particles from side to side. People sometimes build fences to keep sand from shifting so much. Eventually, the sand is blown away and water takes its' place. The land is gone.
Factors that influence erosion rates
The ability of waves to cause erosion of the cliff face depends on many factors.
The hardness or ‘erodibility’ of sea-facing rocks is controlled by the rock strength and the presence of fissures, fractures and beds of non-cohesive materials such as silt and fine sand.
The rate at which cliff fall debris is removed from the foreshore depends on the power of the waves crossing the beach. This energy must reach a critical level to remove material from the debris lobe. Debris lobes can be very persistent and can take many years to completely disappear.
Beaches dissipate wave energy on the foreshore and provide a measure of protection to the adjoining land.
The stability of the foreshore, or its resistance to lowering. Once stable, the foreshore should widen and become more effective at dissipating the wave energy, so that fewer and less powerful waves reach beyond it. The provision of updrift material coming onto the foreshore beneath the cliff helps ensure a stable beach.
The adjacent bathymetry, or configuration of the seafloor, controls the wave energy arriving at the coast, and can have an important influence on the rate of cliff erosion. Shoals and bars offer protection from wave erosion by causing storm waves to break and dissipate their energy before reaching the shore. Given the dynamic nature of the seafloor, changes in the location of shoals and bars may cause the locus of beach or cliff erosion to change position along the shore.
Coastal erosion has been greatly affected by the rising sea levels globally. There has been great measures of increased coastal erosion on the Eastern seaboard of the United States. Locations such as Florida have noticed increased coastal erosion. In reaction to these increases Florida and its individual counties have increased budgets to replenish the eroded sands that attract visitors to Florida and help support its multi-billion dollar tourism industries.
About this special place
At this special point you will see a very interesting sculpture caused by ..... erosion.
It is a rock of basalt, 15 m high with holes on two spots.
It is said , that this sculpture was a troll turned to stone when he threw stones at the cloister of þingeyrar.
You can go down to the sea level but be careful.
Questions to answer:
1. From the parking place go down to sea level and have a look at the beach.
What is the consistence of this beach? Describe the colour, shape and size of the forming elements of the beach and explain in your own words how these elements were formed.
2. Could you please tell me which animal you have in mind when you look at the sculpture standing in the sea.
3. Explain in your own words how this special form could have been formed.
4. Look at the base of this sculpture. What do you think will happen there in the future due to ...... erosion? Please explain your opinion.
If you place a photo to your log PLEASE do not take a picture of the whole rock. only a section of the rock.
Old holiday-logs are wellcome if you still can fullfill log-conditions.