Remember, as a member of the Science Bus Club you can ‘Ask Albert’ a question about any of the topics. So if you’re not already a member join today!!
Looking At Rocks
Did you know that just like water, rocks have a cycle which can last millions of years. The next time you look at a rock remember that it is probably millions of years old.
Gather as many rocks as you can and have a look at them. Rub different rocks together: are they hard or soft? Do they break or stay as they are. A scientist that studies rocks is called a geologist.
- Using Materials
You can group rocks in three main types:
Sedimentary rocks
- Igneous rocks
- Metamorphic rocks
Sedimentary Rocks
For thousands, even millions of years, little pieces of our earth have been eroded (broken down and worn away by wind and water). These little bits of our earth are washed downstream where they settle to the bottom of the rivers, lakes and oceans.
Layer after layer of eroded earth is deposited on top of each. These layers are pressed down more and more through time, until the bottom layers slowly turn into rock.
Types of sedimentary rocks are:
Sandstone
Sandstone rocks are sedimentary rocks made from small grains of the minerals quartz and feldspar. They often form in layers as seen in this picture. They are often used as building stones
Limestone
Limestone rocks are sedimentary rocks that are made from the mineral calcite which came from the beds of evaporated seas and lakes and from sea animal shells. This rock is used in concrete and is an excellent building stone for humid regions.
Shale
Shale rock is a type of sedimentary rock formed from clay that is compacted together by pressure. They are used to make bricks and other material that is fired in a kiln.
Conglomerate
Conglomerate rocks are sedimentary rocks. They are made up of large sediments like sand and pebbles. The sediment is so large that pressure alone cannot hold the rock together; it is also cemented together with dissolved minerals.
Gypsum
Gypsum rocks are sedimentary rocks made up of sulphate mineral and formed as the result of evaporating sea water in massive prehistoric basins. It is very soft and is used to make Plaster of Paris, casts, moulds and wallboards.
Igneous Rocks
Igneous rocks are called fire rocks and are formed either underground or above ground. Underground, they are formed when the melted rock, called magma, deep within the earth becomes trapped in small pockets. As these pockets of magma cool slowly underground, the magma becomes igneous rocks.
Igneous rocks are also formed when volcanoes erupt, causing the magma to rise above the earth's surface. When magma appears above the earth it is called lava. Igneous rocks are formed as the lava cools above ground.
The main types of Igneous rocks are:- Granite
- Scoria
- Pumice
- Obsidian
Granite
Granite rocks are igneous rocks which were formed by slowly cooling pockets of magma that were trapped beneath the earth's surface. Granite is used for long lasting monuments and for trim and decoration on buildings.
Scoria
Scoria rocks are igneous rocks which were formed when lava cooled quickly above ground. You can see where little pockets of air had been. Scoria is actually a kind of glass and not a mixture of minerals.
Pumice
Pumice rocks are igneous rocks which were formed when lava cooled quickly above ground. You can see where little pockets of air had been. This rock is so light, that many pumice rocks will actually float in water. Pumice is actually a kind of glass and not a mixture of minerals. Because this rock is so light, it is used quite often as a decorative landscape stone. Ground to a powder, it is used as an abrasive in polish compounds.
Obsidian
Obsidian rocks are igneous rocks that form when lava cools quickly above ground. Obsidian is actually glass and not a mixture of minerals. The edges of this rock are very sharp.
Metamorphic Rocks
Metamorphic rocks are rocks that have "morphed" into another kind of rock. These rocks were once igneous or sedimentary rocks. How do sedimentary and igneous rocks change? The rocks are under tons and tons of pressure, which fosters heat build up and this causes them to change. If you exam metamorphic rock samples closely, you'll discover how flattened some of the grains in the rock are. There are mainly two types of metamorphic rocks, schist and gneiss.
Schist
Schist rocks are metamorphic. These rocks can be formed from basalt, an igneous rock; shale, a sedimentary rock; or slate, a metamorphic rock. Through tremendous heat and pressure, these rocks were transformed into this new kind of rock.
Gneiss
Gneiss rocks are metamorphic. These rocks may have been granite, which is an igneous rock, but heat and pressure changed it. You can see how the mineral grains in the rock were flattened through tremendous heat and pressure and are arranged in alternating patterns.
Rock Is Everywhere
Rock is everywhere. If you don’t believe me, go outside and have a look around. Look at the walls of your house, your driveway. Look at cliffs, quarries, mountains with rock faces, fields/moors with rocky outcrops, muddy fields, town streets. Can you see the rocks?
Different Types Of Soil
The only thing you need to keep in mind here is that there are different types of soil and that difference is dependant on the rocks the soil was made from. Clay, loam, chalk are all examples of soil.
Looking At Soil Samples
In order to look at soil samples you will have to gather many different samples. Check them out for texture, large particles or small particles etc. You will need some sieves. After you sieve the dry soil what do you see? Contact the Science Bus and tell Albert your story.
Measuring The Permeability (Per-Me-Ability) Of Soil
Have you ever seen puddles in fields or floods on different surfaces? Did you know that water flows more quickly through sand than clay? Why do you think that is? Ask Albert and he will explain. You can do loads of experiments with sand, soil and water to measure and test how fast water passes through the soil.
Erosion
Erosion happens when rocks are affected by outside processes. For instance, mountain rock is eroded away by weather. Did you know that millions of years ago the Pennines were probably as high as Mount Everest is today? Wow! Rocks are constantly being eroded away. If you go to the seaside have a look at the rocks on the beach. The erosion of the sea means the rocks are nice and round, with no sharp surfaces. Ice and wind also erode rocks.
Remember, as a member of the Science Bus Club you can ‘Ask Albert’ a question about any of the topics. So if you’re not already a member join today!!
