Friday, October 2, 2009
Thanks
Thank you for looking at my site, I appreciate it a lot. Thank you to all the sites which I got information from and the sites where I got pictures and videos from.
Volcanoes
There are lots of old extinct, volcanoes in Ireland. These range in age from the underwater volcanoes in Counties, Waterford and Wicklow (480 million years ago) to the volcanoes that erupted to form the Giant's Causeway in Co. Antrim (55 million years ago). There are lots of volcanic rocks present near Limerick and Counties Mayo and Galway. This shows that here, in Ireland we did have a past with volcanoes and volcanic eruptions.
Monday, September 28, 2009
Although Mars appears cold and lifeless today, it obviously had a past with active volcanoes. That's because there are many extinct volcanoes on Mars. In fact, the largest volcano in the Solar System is on Mars, its called, Olympus Mons.
When you're looking at all of the surface of Mars, captured from space, there are 4 huge volcanoes that you can see in the Tharsis region of Mars. Olympus Mons is the largest, and the other 3 are Ascraeus Mons, Pavonis Mons, and Arsia Mons. While Olympus Mons towers 24 km above the surrounding plains, and spans 500 km across, these smaller volcanoes are merely 350-450 km across and stand 15 km tall.
These are just the largest, but there are a total of 20 named volcanoes across the surface of Mars.
Like the Moon and Mercury, Mars shows no signs that it ever had active plate tectonics. One of the most obvious features of plate tectonics on Earth is long mountain chains, where plates are rubbing against each other. This doesn't seem to have existed on Mars.
Nobody really knows why the volcanoes are Mars are so big, but it probably has something to do with the lack of plate tectonics. Without the movement of plates, hotspots were able to stay in one place and just grow and grow for millions of years.
It's possible that the volcanoes on Mars still active, but they haven't erupted in the last few million years. By counting impact craters, scientists can find out how old a part of Martian terrain is. Regions around Olympus Mons are as young as 100 million years old. Since that's only 2% the age of Mars,the volcano has been erupting for 98% the history of the planet, so why would it stop now?
When you're looking at all of the surface of Mars, captured from space, there are 4 huge volcanoes that you can see in the Tharsis region of Mars. Olympus Mons is the largest, and the other 3 are Ascraeus Mons, Pavonis Mons, and Arsia Mons. While Olympus Mons towers 24 km above the surrounding plains, and spans 500 km across, these smaller volcanoes are merely 350-450 km across and stand 15 km tall.
These are just the largest, but there are a total of 20 named volcanoes across the surface of Mars.
Like the Moon and Mercury, Mars shows no signs that it ever had active plate tectonics. One of the most obvious features of plate tectonics on Earth is long mountain chains, where plates are rubbing against each other. This doesn't seem to have existed on Mars.
Nobody really knows why the volcanoes are Mars are so big, but it probably has something to do with the lack of plate tectonics. Without the movement of plates, hotspots were able to stay in one place and just grow and grow for millions of years.
It's possible that the volcanoes on Mars still active, but they haven't erupted in the last few million years. By counting impact craters, scientists can find out how old a part of Martian terrain is. Regions around Olympus Mons are as young as 100 million years old. Since that's only 2% the age of Mars,the volcano has been erupting for 98% the history of the planet, so why would it stop now?
How are volcanoes formed?
Volcanoes are really big mountains that build taller and taller, after a while, they might erupt. This means that the molten rock in the bottom of the volcano, magma, comes from within the earth and erupts onto the surface. It will come up through the earth’s surface through, the easiest gap in the earths surface. The volcano might be explosive and produce ashes and lava. The explosions are usually first because there are lots of gases inside the magma. When you have a bottle of soda pop, you do not see any bubbles of gas, but when you open it, bubbles form almost instantly. Once the gas bubbles have all escaped, the soda is flat. Once the magma is flat, a lava flow comes out. Most of the volcanoes from around the Pacific Ocean are composite, which means that there are layers of ashes and lava. Most volcanoes are 10,000 to 100,000 years old — it takes time for them to grow big.
Volcanoes are really big mountains that build taller and taller, after a while, they might erupt. This means that the molten rock in the bottom of the volcano, magma, comes from within the earth and erupts onto the surface. It will come up through the earth’s surface through, the easiest gap in the earths surface. The volcano might be explosive and produce ashes and lava. The explosions are usually first because there are lots of gases inside the magma. When you have a bottle of soda pop, you do not see any bubbles of gas, but when you open it, bubbles form almost instantly. Once the gas bubbles have all escaped, the soda is flat. Once the magma is flat, a lava flow comes out. Most of the volcanoes from around the Pacific Ocean are composite, which means that there are layers of ashes and lava. Most volcanoes are 10,000 to 100,000 years old — it takes time for them to grow big.
Monday, September 21, 2009
Volcanoes
The name "volcano" came from the name of Vulcan, who was a god of fire in Roman mythology.
As the pressure in molten rock builds up it needs to escape somewhere. So it forces its way up “fissures” which are narrow cracks in the earths crust. Once the magma gets through a crack in the earth’s surface it’s called lava.
As the pressure in molten rock builds up it needs to escape somewhere. So it forces its way up “fissures” which are narrow cracks in the earths crust. Once the magma gets through a crack in the earth’s surface it’s called lava.
Friday, September 18, 2009
Pyroclastic flows
A Pyroclastic flow is a devestating effect of a volcanic eruption and its quite common too. It is a fast flowing, hot moving current packed with gas and rocks. The flows can get as hot as 1000degreeC. The flows travel down the hill of the erupted volcano almost hugging the ground or spread laterally due to gravity. The speed of the flow depends on a few things they are the density of the current, the rate at which the debris are spat out of the volcano and the slope at which it travels down. The flows that contain more gas than rocks are known as " fully diluted pyroclastic density currents". A pyropclastic flow happened at Mount Pelee and in the city of St-Pierre and killed nearly 30,000 people.
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