Geology

Earth's mantle - what is it made of - well, many things indeed, but mainly the following:

Compounds of the following metals or semi-metals, along with oxygen compounds:

1) Iron compounds

2) Magnesium compounds

3) Aluminum compounds

4) Silicon compounds

Generally, the relation is this - the further from the surface the colder the water.

This makes sense because of course as you go down further there is less and less sunlight, and therefore the temperature of the water drops.

In fact, it is a bit like considering when a few grains of sand become a heap of sand: there is no absolute point where something turns from a depression to a canyon.

The definition is simply a deep, narrow steep-sided valley, but the minimum depth is not absolute.

The difference between precious and semi-precious comes down purely to human definitions that have been imposed.

There is nothing in and of itself about the nature of a stone, which makes it precious or semi-precious.

Rather it is down to human desirability of an element or mineral or form or a stone that decides.

Generally, the rarer and more sought after a mineral is, the more likely it is to be defined as precious.

Desired, but more common and less valuable items may be, in contrast, semi-precious.

This is to do with light and the atmosphere.

The way the rays of light strike the mountains at a greater height than us, then reflect and reach our eyes below the height of mountains, coupled with the air in-between, leads to them looking purple, in a similar way to the process with different wavelength light makes the sky look blue on a sunny day.

The rate of species depends on the time and particular species and environment at the time, therefore there is no one absolute figure that can be used.

However clearly the rate of species can be used to estimate where in transition each species is and when the next variations will come along.

Magma is part of the layer just under the crust.

It reminds us that whilst everything seems solid underfoot actually that is not quite so, and there are only relatively thin layers on top that move and float on a sea of magma underneath, it is this that moves the continents around the surface of the planet, all be it very slowly indeed.

The largest volcano in the world over ground is called Mauna Loa.

Mauna Loa is to be found in Hawaii, now a US State.

There is a gradual transition caused by a change in temperature and reducing pressure.

Tall structures and things that are metal attract lightning, also trees do.

In fact, anything that is metallic containing mineral may seem to attract the lightning for instance things like iron.

Carbon 14 has a half-life of 5,730 years, and therefore it can be used to date very accurately a large majority of things, particularly wood and so on.

It is only not useful for ancient things where all the carbon 14 will have gone, or almost gone - and for these there are other isotopes of other elements, that can be used with a much longer half-life.

This is due to the heat generated from the earth's interior and earthquakes - the convection currents deep within the earth because the movement of the material that sits on top.

Igneous rocks - got to that stage of your geography or chemistry class already?

Well here is a little information for you on the ways in which igneous rocks can form.

Igneous rocks are created when melted material crystallizes, e.g. from magma.

There are two formation methods, the first is that they form on the surface and these are called extrusive igneous rocks, or they can form inside the crust, and these ones are called intrusive igneous rocks.

The oldest sea floor in the Atlantic that is made of basalt is to be found closest to the continents, the further into the ocean away from land that you go, the newer the sea floor.

This is because new sea floor is still being added in the middle of the ocean and therefore the banding and age of the rocks gets increasingly older the further you move from the centre of the ocean.

This is the Great Barrier Reef off the northeast corner of Australia.

These are a mountain range, along Zaire and Uganda in East Africa.

The lower section of the Earth's crust has been reached. The possibility of the mantle is not far away. Depths of over 4,500 feet have been reached.

Well each type of volcano can be very destructive and if you are talking in human loss of life terms than the answer is any type of volcano that is near dense population.

The most destructive type of volcano though that is generally acknowledged; as such, independent of people is that which is called the stratovolcano.

This begins to form when tiny marine animals - coral polyps - attach themselves to rocks on the seabed.

This is because of the way that it is formed. When you have a rock that is formed through metamorphosis then it has been created through heat and pressure acting on other rocks.

Fossils are inherently delicate things and therefore precious little would withstand the conditions that are required to create marble - and therefore marble hardly ever contains fossils as a direct result of this.