dimanche 13 mai 2012

The Stromatolites (Shark Bay)


In June 1954, a group of geologists discovered the stromatolites or ‘living rocks’ of Hamelin Pool which linked life on Earth today, with life on Earth 3.5 billion years ago.
Scientists who have studied fossils of stromatolite, once believed them to have been wiped out by intense competition with newer life forms like ants and animals.
While competition dramatically reduced stromatolites worldwide, 550 million years ago, Hamelin Pool has provided a safe haven for stromatolite colonies for the past 5000 tears.
Stromatolites are layered limestone rock built by single-celled cyanobacteria (blue-green bacteria), which trap and bind sediments. Some build craggy towers, others build flat spongy mats.
At the entrance to Hamelin Pool is a massive sand bar called the Fauré Sill, which has built up over 6000 years and restricted the tide flow into the Pool.
The shallow waters of Hamelin Pool evaporate quickly and create super salty water. In such harsh conditions, few sea snails can survive to graze on cyanobacteria.
Hamelin Pool has become a safe neighbourhood for cyanobacteria which build stromatolites of various shapes and sizes at different water depths.

Red Caps. 
These red-capped stromatolites stopped growing about 500 to 1000 years ago when the sea level fell. The reason for their colouring is a family mystery. It may have been because of iron in the water as they grew or the pigment of visiting bacteria.

Layers of history
Stromatolite layers grow outwards, like the growth rings of a tree. The outer layer remains a thin strip of active life with a sticky film to trap and bind drifting shells and sand. They slowly build up layers which harden into rock.
Scientists believe that the internal growth rings provide information on local environmental changes during the stromatolites lifetime. Some scientists say that the growth rings of very ancient stromatolites reflect changes in the length of days, angle of the sun, even the rate at which the earth rotated.

Living rock
The cyanobacteria that build us first appeared n earth 3.5 billion years ago when oxygen was scarce. As the original stromatolite colonies expanded, they released more and more oxygen into the atmosphere, eventually raising the oxygen level to 20% of all atmospheric gases. This led the way for air-breathing life forms to evolve.
When the tide is in, you can see little bubbles.
It was amazing to see these stromatolites, and to think that we live are alive on earth today is thanks to them is fascinating!
..............

We spent the night at the Hamelin Bay Station. It was really nice and calm there, and the owners were very friendly. It is in the middle of nowhere though! We wanted to go and buy some food but were told that the closest shop was more than 100km away!

There were some black swans on the lake! 
The black swan is the state emblem, and the Swan River was named after it, but sadly had very few, because most of the swan’s preferred habitat, the shallows, has been destroyed.



Le Carnet de Voyage
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Shell Beach (Shark Bay)

On this beach there is no sand, only shells!

Here millions of small white Coquina Shells have accumulated over time to create this unique environment. It is estimated that in some spots the shells are 10m deep. The beach stretches for over 120km around L’Haridon Bight.
Coquina limestone is a natural composite of calcite crystals and shell. Many of Shark Bay’s historical buildings used blocks of this in their construction.

A beach of shells is really rather unique! It does hurt your bare feet a bit though!


Le Carnet de Voyage
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National Park Francois Peron - Shark bay

Francois Peron National Park, so named after the French zoologist Peron, who arrived in Shark Bay in 1801 on the Geographe under Captain Baudin. Baudin led the expedition to the Great South Land, accompanied by Captain Hamelin in the Naturaliste. Peron’s observations during his visits to the area proved to be of great importance to the natural history of the region.
The national park covers 52 500 ha of the northern most tip of the Peron Peninsula. It was once a sheep station developed in the 1880’s; but was purchased by the State Government in 1990 to create the park.

The access to the park is by 4WD only.
At the entrance, you must deflate tires. 
It’s time to hit the sand! 

A guy actually deflated my tires for me (he must of thought I was some dumb blond in a 4WD, but nice anyway!). He told us that the track was really boggy and that you had to keep ploughing though in low gear not to get bogged in. 
This kind of freaked me out a bit. The sand was so thick in places! And I was so scared that I would get stuck! 
This fear made me drive stupidly. I stuck in low gear the hole time, for nearly 40km. The jeep started to overheat. 
I just blasted hot air into the car to try and cool her down. It worked a bit, but the boiling hot air was burning me. I felt like I was skidding everywhere. On every bump I thought that I would get stuck. 
Even worse, the boys couldn’t wait for me because they would be driving in a too lower gear for their Toyota (so was I actually). I wasn’t having fun at all. I was on my own and scared. I just kept on shouting ‘come on little jeep! You can do it!!’ In the end, I got fed up and stopped at a camping area to have some lunch.
I knew that the guys were waiting for me at the end of the track. 
I really hesitated about continuing. Once having gathered all my courage, I set off again. 
This time I was confident. I wasn’t scared anymore! I was in gear 3, flying over bumps! The gear was right so the jeep wasn’t overheating. I was having so much fun!!
I was so glad that I did that drive.
The landscapes of Cape Peron were dramatic. 
Magnificent red sand dunes with brilliant white sand dunes are a beautiful contrast against the aqua blue ocean. 

There is lots of wildlife at Cape Perron.

The water was so crystal clear. A real naturel aquarium!
In the water we saw dolphins, turtles, flying fish and even sharks!
Turtle
Shark

We slept in the park that night. Sadly we didn’t see any bilbys (sort of rats with really big ears!

The next day we headed back, but did an extra 20km of sand tracks to see the Big Lagoon.
Yet again the colors of the sea were magnificent!

Then it was time to get back onto bitumen roads again...




Le Carnet de Voyage
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