Geology

The picture below is a scan of a coloured slide I took a number of years ago. The quality isn't brilliant but it wlll hekp me give you a little more information.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

The east coast of the island of Oahu, Hawaii gives you an idea of how rugged volcanic coasts can be. Many locations in Hawaii have been used in movies and television shows. "Lost" and "Jurassic Park", for example, made use of Hawaii's rugged and beautiful locations.

The Hawaiian islands are located over what is known as a hotspot*. Over millions of years, the movement of the crust has caused volcanoes to appear in a chain. Look at the Google Earth image below. Stretching away to the north-west, you can see the chain of submerged islands that may once have been above the water. Google Earth allows you to see these. It's a great way of looking for geological features on a large scale. Have you already loaded it so you can zoom in?

The hotspot is still very active. A large new volcano is already growing beneath the ocean to the south of Hawaii and will most likely one day be seen above the ocean surface. We have a very active world beneath us.

Link for hotspot:

http://en.wikipedia.org/wiki/Hotspot_%28geology%29

Want Google Earth... go to:

http://www.google.com/earth/index.html

 

Hello Year 6,

This post is to give a little information about the last two of six samples you should soon have.

Iron Sands

The small iron sand sample I've sent came from a riverside beach on the North Island of New Zealand at a place called Awakino. You can use Google Earth to locate the river mouth in the photo below.

Iron sands (or titanomagnetite) were eroded from volcanic rocks and washed down rivers. The sands can vary in iron content but at Awakino are 95+% iron. The sand is very easily picked up by magnets but is hard to get all of it off again so if you try to pick the sand up with a magnet, wrap the magnet in paper to make it easy.

Iron sands are mined in places because of their high iron content. The site below gives some more information...

http://www.ttrl.co.nz/cms.aspx?page=What_are_Iron_Sands&flag=1

The picture below has been scanned from a slide taken over 25 years ago on one of my trips to see New Zealand's sights and especially the volcanic areas of the North Island.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Pumice Stone

Pumice is a 'frothy' lava formed when super-heated lava under high pressure mixes with water such as in underwater volcanic eruptions. When the lava is released, the sudden change in pressure and rapid cooling form gases in the cooling rock. The pumice stone is very light and can float on water.

I think the pumice stone I have sent you came from an underwater eruption near Tonga in about 1984. Huge rafts of the pumice floated towards Fiji, some even making it to the shores of Australia where I found the sample on a beach.

For more information on pumice, the Wikipedia link below may help

http://en.wikipedia.org/wiki/Pumice

Remember you can check out Tonga and Fiji using Google Earth. The image below shows Fiji and Tonga. You can see Tonga is really the tops of peaks in an underwater mountain range. You can use Google Earth to view other areas. Try places such as Hawaii's Big Island, Yellowstone National Park in USA, Mount Etna, Mount Vesuvius, Iceland, Mount Kilamanjaro and any other volcanoes or thermal areas of interest. Google Earth can almost take you inside.

 

In this post, I'm going to show you some photos taken of an active volcanic area on The Big Island of Hawaii. The island is the real Hawaii but, as most people think of all the isalnds as Hawaii, they tend to call it The Big Island.

Here is a link to information about The Big Island...

http://www.gohawaii.com/big-island/regions-neighborhoods/kau/hawaii-volcanoes...

The photos below were taken of lava flows on Kilauea, one of the world's most active volcanoes. Tourists aren't allowed to get too close to lava flows because of the danger so these came care of a friend. I will later post some taken by me from the safety of a helicopter above a caldera*.

* http://en.wikipedia.org/wiki/Caldera

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These photos show pahoehoe lava flows. Being cooler, the darker colour flows ooze out of the lava tubes like honey from a tipped jar.

 

The following two photos were taken from a helicopter. As the flowing lava hits the sea water, clouds of steam are formed as the water boils. The constant flow of lava adds to The Big Island.

Below is a Google Earth image of Hawaii. If you download Google Earth to your computer you can zoom in on Mauna Loa, Mauna Kea and Kilauea volcanoes.

Hello Year 6,

The small samples of scree and obsidian are from New Zealand's volcanic areas on the North Island.

I am not sure exactly where the obsidian came from but I know it can be found in the crater although people aren't permitted to collect it there. I have seen samples in the crater. The piece I have and the small sample I've sent were bought at a rock shop.

The scree sample is from the crater and is an accidental collection example. When in Rotorua, New Zealand, you can book to go on a tour of the crater. You are driven up to the crater edge by 4WD cars before hiking up along the crater rim then  making a steep descent through scree to the bottom of the crater.

When I say a quick descent, you follow a steep track over the crater rim then make large strides in the scree. Each step seems to be over a metre in length as you move along.Care has to be taken as it is a long way to roll to the bottom if you fall.

On arriving back after the trip, I found many bits of scree had been caught in clothing and boots. They became my collection of scree.

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Obsidian - volcanic glass -

http://en.wikipedia.org/wiki/Obsidian

Scree - or talus, is broken rock fragments. The scree in the crater was made when the Mt Tarawera erupted in 1886 -

http://en.wikipedia.org/wiki/Scree

Mt Tarawera, New Zealand -

http://en.wikipedia.org/wiki/Mount_Tarawera

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A great way to view volcanoes is to use Google Earth. The satellite images can let you look down craters.

Here is a link to Google Earth. You would need to download it.

http://www.google.com/earth/index.html

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Image 1: A screen capture of Google Earth viewing Mt Tarawera, New Zealand.

If you load the full sized image, you can see a rectangle drawn on the screen shot of Mt Tarawera. The rectangle roughly shows you where the next photo shows, inside the crater.

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Image 2: A photo I took when I was on a tour into the crater of Mt Tarawera. I was standing on the eastern rim of the crater and was looking west. The arrow points to a group of people on the far side. They are about to make their way into the crater. Their size can give you an idea of how large that part of the crater really is. You can make out the track. It's quite an experience.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

I have organised a few family trips to New Zealand for families in schools where I've taught. The thermal areas and volcanoes are wonderful.When I took this photo, I had some students with me. They were worried the volcano might erupt while we were in it. At that time, the volcano had erupted just over 110 years before.

I smiled and said, "It erupts about every 110 years so we're safe.... Wait a minute, it's due now."

The boys I was talking to knew me well, "Sure," they said with a smile.

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Hello Year 6, High Lawn.

I have a package ready to send to you on the next mail. It should arrive by the end of next week (September 30) if all goes well. The package contains six small samples I've collected over a number of years.

This initial post on this blog is to let you know a little about what is arriving. I will make more posts with greater details as I get time. At first, the posts will let you know what each sample is, how and where I collected it and a little bit about the place I collected it.

Later posts will include photos and video clips I've taken in and around volcanic areas in New Zealand and Hawaii (the Big Island). I'll also try to add links to sites or video clips that may be of use or show what I am posting.

I hope you like the samples. The photos were taken on a grid where each square is 1cm by 1cm so you can see the sizes.

 

Scree from New Zealand. I collected this almost accidentally while making my way down to the bottom of a volcano crater.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Obsidian or volcanic glass. Again, this sample is from New Zealand. It also came from a volcanic crater although this was part of a piece I had bought.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Iron sands. I collected this from a beach on the North Island of New Zealand. there, the beach is black with sand almost 100% pure iron. It can be picked up by a magnet. Despite being iron and in salty water, it doesn't rust and is much better to use than iron filings when playing with magnets.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Pumice. This is a very light rock which, if I remember correctly, came from a volcano under the ocean near Fiji. Large amounts in the underwater eruption floated to Australia. I collected this from a beach. A number os on the back of it. This was just a spare numbered sample from my collection.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Pahoehoe is one of the types of lava from an Hawaiian volcano. Once cooled, it is the easiest to walk on. It breaks down into black sand.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

'a'a is the second type of lava coming from hawaii. It tends to have sharper edges and is harder than pahoehoe. I like to think it's named that because of the sound you make if you walk on it barefoot when it is cooled.

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I hope you like your little collection from the other side of the world. My home town here was once a volcanic region but this was many millions of years ago. I see many traces it was once active but the above samples are much more recent and from active volcanoes. More on this later.

Ross Mannell (teacher)

Australia