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Coastal Features

Assignment on Blowholes
by

Nicholas Welch

on 20 September 2012

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Transcript of Coastal Features

Coastal Features Blowholes Formation of blowholes Location of Blowholes Blowholes can be found all over Australia's coastline and also abroad. Wherever a sea cave has formed, there is potential for a blowhole to be created in the structure.
Most of the larger, more spectacular blowholes are located on Australia's east coast throughout New South Wales, Victoria, Queensland and Tasmania.
The Kiama Blowhole in NSW is one of the worlds biggest blowholes that can spray a jet of water 60m into the air.
La Bufadora in Mexico is a blowhole that can spurt water every minute. This blowhole is very powerful as it can still reach over 30m and can erupt frequently.
There are other popular blowholes in Australia such as, Cape Bridgewater; VIC, Whale rock; QLD and Albany in WA.
There are blowholes along the western side of Robe in south Australia along with many other coastal features. Igneous Rock Sediment Weathering Sediment Rock Compaction Weathering Metamorphic Rock Heat and Pressure Magma Melting Cooling Melting Heat and Pressure Weathering Blow holes in action! The Rock Cycle Bibliography A sea cave in the side of a cliff or other coastal feature has to be present for a blow hole to be able to form. At high tide, water enters these caves and the constant pressure of the waves, erodes deeper into the sea cave.
The water eventually moves up and begins eroding the roof of these cave. An opening forms on the roof of the cave, through to the top of the cliff. This creates a pipe which is a bit like a chimney, down into the sea cave, from the surface.
Air must be able to pass through the pipe and into the cave for a blow hole to occur. Blow hole cross section Sea cave entrance Igneous Rock Igneous rocks are the oldest form of rocks and are formed from magma. In the center of the earth all the minerals are in a liquid state, and the magma rises to the surface away from the heat into cooler rock.
Depending on the speed that the magma is cooled, defines how large the crystals will be. Magma cooled very quickly will form a fine solid rock with small crystals.
Sometimes it can be cooled so fast that it forms a black glass that you cannot see through.
When it is
cooled slowly, the crystals are very large and visible like in granite. How does tourism affect blowholes Sedimentary Rock Sedimentary rock is formed through deposition and a build up of sediments. Sediments like sand, fine grains and mud, are pressed together and compacted. This forms the sedimentary rock and is the reason that it can be eroded easier than other forms of rock.
Some sediments are glued together to form rock by other minerals. The minerals are dissolved in water and this bonds the sediments together.
The same type of rock can have a different appearance depending on the minerals and how the rock was formed. Some sea caves empty completely at low tide, Wikipedia, Viewed 12/9/12, http://upload.wikimedia.org/wikipedia/en/thumb/8/80/Seacave_cathedral.jpg/250px-Seacave_cathedral.jpg Australian Geographic, viewed 13/9/12, Six of the best blowholes, http://www.australiangeographic.com.au/journal/six-of-the-best-blowholes.htm Size of blowholes The size and furiosity of a blowhole depends on the size of the sea cave and where it is located along the coast line. Blowholes that are exposed to the elements and the rough sea will tend to be much more powerful and spout higher in the air than the caves located in inlets and calmer waters. The sea caves that are located in these calm waters are also a lot smaller as they haven't been exposed to the corrosive winds and sea and erosion hasn't been as effective. Large caves are generally formed extremely slowly in igneous rock such as basalt. This rock is tough and can be formed deep into a cliff with out collapse like a sedimentary rock might. on weaker rock such as sedimentary surfaces, the erosion will erode allong the entire cliff face and will not penetrate deep in to the cave. Sedimentary rocks, Oracle Think Quest, Viewed 14/9/12, http://library.thinkquest.org/J002289/sed.html Erosion Erosion takes place very slowly and also in many forms. Erosion can take place in ways such as wind erosion, water erosion and this can mainly happen along coastlines as there can be strong winds and rough seas.
Many coastal features are formed through erosion such as, caves, blowholes, stacks, arches and more.
Wind erosion mainly occurs in arid desert areas and can happen in two ways. Grains of dirt or rock can be shaped by the wind blowing them away to form new shape to the land. Wind erosion can also force this dirt and rocks in to other surfaces that over time, will erode the surface.
Coastal erosion can also occur in many ways through the power of waves. Waves pounding into a crack in a rock can cause the air inside to become compressed. this can crack the rock further. Waves that are very powerful can break of chunks of rock on a surface and shape the coast over time.
The fastest form of coastal erosion is abrasion when waves pound rock and sediment at a surface that causes friction. this can also result in deposition as well. Erosion, viewed 17/9/12, wikipedia, http://en.wikipedia.org/wiki/Erosion Coastal Erosion Wavecut platform southerndown pano, viewed 17/9/12, wikipedia, http://upload.wikimedia.org/wikipedia/commons/thumb/6/63/Wavecut_platform_southerndown_pano.jpg/800px-Wavecut_platform_southerndown_pano.jpg Deposition Deposition occurs through the deposit of sediment along a coastline. Just like erosion is taking away from the shore line and reducing it, deposition is washing sediments back and forming a coast line.
Deposition occurs when forces such as wind and water, can not over come the mass and friction of the sediment. This causes a build up of sediments in layers that forms the body of land.
These sediments can be compressed together in the layers and form in to sedimentary rock.
Substances like coal are formed through the deposition of organic materials like plants and plankton. the materials build up as they are deposed, and then under pressure, over millions of years, form coal.
Chalk is formed from marine animals skeletons that builds up over time, through deposition.
The diagram below shows the key areas where deposition mainly occurs. All these areas are on low lying land where sediment;s get blow or washed into. These areas are also where many coastal features are formed where sediments have built up. Metamorphic rock The term metamorphic comes from greek meaning: change, form. Metamorphic rocks are deep under the earths surface and require heat and pressure to form. Other forms of rocks that have being melted by magma will change form to a metamorphic rock. Both sedimentary and igneous rock can change into this form. This transformation is also very slow and takes place over millions of years. As metamorphic rock is formed deep in the earth, they very rarely have fossils in them and are usually composed of only one mineral. Quartzite, slate and marble are metamorphic rocks that were once sedimentary. Metamorphic rocks, viewed 19/9/12, Oracle Think Quest, http://library.thinkquest.org/J002289/meta.html Pictures Media All of the blowholes around the world become a major tourist attraction for the town. This can be very good economically and it can help put small towns on the map. Blow holes can also be very dangerous for visitors witnessing one erupt.
La Bufadora blowhole in Mexico is a very popular attraction. The blowhole is so powerful that it can blow people off their feet. This can be dangerous at the blowholes edge along the rocky boulders, as there is a risk of falling in. Blowhole at Kiama, viewed 20/9/12, wikipedia, http://upload.wikimedia.org/wikipedia/en/3/3a/BlowHoleAtKiama.jpg What they are made up of Blowholes can be made up of all three rock types however the power and size of the blowhole can depend on the rock type. Sedimentary rock erodes quickly and can form a cave quickly, but this also means that they can collapse much easier and their structure is much weaker than other rocks.
Igneous coastlines erode very slowly as the rock surface is very tough. This allows a blowhole to become much larger as the rock can hold and wont collapse. This also means that large blowholes are very old as the igneous rock takes time to erode. Latite and bassalt are igneous rock which is the most common rock for blowhole formation. Kiama Blowhole, viewed 20/9/12, Enjoy this World, http://www.enjoythisworld.com/NewSouthWales/KiamaBlowhole/tabid/449/Default.aspx The history of Kiama Blowhole The Kiama blow hole is located on NSW's east coast and attracts more that 600,000 tourist every year. The Kiama blowhole has a long history with the native aborigines in the area as it was a major meeting place for their people. The name originate from the aboriginal language that means 'Where the sea makes noise', Kahnterinteree.
George Bass was the first european settler to witness the blowhole as he docked on the coast. He was on his way to bass strait on a whaleboat. He discovered the blow hole on the 6th of December 1797.
A performer named Charles Jackson, walked across the blowhole on a tight rope and attracted many visitors in 1889
The soil around Kiama was volcanic and rich. This provided perfect farming conditions when Australia was being colonised by the european settlers. South coast Victoria, viewed 20/9/12, Kiama Blowhole, http://www.south-coast-vacation-packages.com/kiama-blowhole.html Kiama, New South Wales, viewed 20/9/12, wikipedia, http://en.wikipedia.org/wiki/Kiama,_New_South_Wales Wollongong Kiama Blowhole, 6 Apl 12, viewed 20/9/12, Youtube http://www.yoube.com/watch?v=D5v58UKGifQ&feature=fvwrel Bicheno Blowhole - think-tasmania.com, Nov 29 10, viewed 20/9/12, Youtube, http://www.yoube.com/watch?v=Co0Jm6cll14 Erosion on a coastline Key Deposition areas Sedimentary environment, viewed 20/9/12, wikipedia, http://upload.wikimedia.org/wikipedia/commons/thumb/a/a3/SedimentaryEnvironment.jpg/800px-SedimentaryEnvironment.jpg Beach erosion, viewed 19/20/12, The role of the beach, http://whyfiles.org/091beach/images/erosiondia1.gif
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