The Rock Cycle

Introduction

Welcome Year 8 Science Students!

 

This WebQuest will be about the rock cycle.

 

Throughout this WebQuest we will learn about the rock cycle and how rocks can change from one type to another over time. Whilst completing the WebQuest, please answer the questions on your worksheet.

At the end of the Quest you will be making you own rock cycle diagram.

 

To begin, click on the task tab and follow the directions.

Once you are done the task go onto the process tab and then the conclusion tab.

The evaluation tab will tell you how you will be graded on your rock cycle diagram. 

 

Happy Rocking!

 

 

 

 

 

 

 

 

Task
Process

The following information can be used to answer the questions on your worksheet. After you have finished, you will be ready to make your Rock Cycle Diagram.

 

Rocks are the most common material on Earth. They are naturally occurring aggregates of one or more minerals.

The three main types of rock are:

  • Sedimentary
  • Metamorphic
  • Igneous

How they are formed characterise their differences

 

Sedimentary
Sedimentary rocks are formed from particles of sand, shells, pebbles, and other fragments of material. The sediment gradually accumulates in layers and over time and hardens into rock. Sedimentary rock is fairly soft and can break or crumble apart. Fossils are often found in sedimentary rock, as well as pebbles, sand or stone.

Examples - sandstone and coal

 

Metamorphic
When the Earth moves, it can cause rocks to be buried or squeezed. This results in rocks being heated and put under pressure. The rocks do not melt, however the minerals they contain can change chemically, formed new metamorphic rocks.

Examples - slate and marble

 

Igneous
On earth, some rocks melt under extreme heat to form magma. As magma is a liquid and is generally less dense that the surrounding solid rock, it moves upwards to a cooler area on Earth. As the magma is cooler, it loses heat and solidifies. Now that it has crystallised, an igneous rock is formed. Magma can cool in two places – on the Earth’s surface (where it has erupted from a volcano – formed extrusive rock) or under the Earth’s surface (intruded on older rocks forming intrusive rock).

Examples – pumice and granite

 

Weathering

Rocks gradually wear away – this is known as weathering

There are three types of weathering:

  • Physical weathering
  • Chemical weathering
  • Biological weathering

 

Physical weathering = caused by physical changes (such as changes in temperature and the effects of wind, rain and waves)

Temperature Changes

When the suns energy heats up a rock, the rock will expand. When the temperature falls, the rock cools down and will contract. This continuous cycle causes pressure on the rocks outer layer leading to cracks (exfoliation)

Water, wind and waves
The force of wind, water or waves can wear down the rocks, causing coarse surfaces to smooth over time or to corrode away. Erosion happens when rocks and sediments are picked up and moved to another place by ice, water, wind or gravity.

Freeze and thaw:
Put a glass of water in a freezer and it will break up. Why? Because water expands when it freezes. The formation of ice can also break rocks. When water gets into cracks in a rock and freezes, it will expand, pushing the crack further apart. When the ice melts, water can then get further into the crack and the process is repeated.  

 

Chemical Weathering = when weathering involves the reaction of some chemicals on rocks

Rain water naturally contains carbonic acid (carbon dioxide in the atmosphere dissolves causing it to be slightly acidic). When acidic rainwater falls on rocks, minerals in the rocks may react chemically, leading them to weather.

Acid rain occurs when carbon dioxide and sulphur dioxide (from air pollution) are dissolved into the moisture in the atmosphere. When acid rain falls on rocks, even more weathering occurs.

 

Biological weathering = when plants and animals wear away rocks (by means of burrowing, walking, weeds growing) causing existing cracks to become wider and deeper leading to pieces of rocks falling away

 

Putting it all together into the Rock Cycle

The rock cycle demonstrates the sequence of processes leading to the formation of different rock types over time. It illustrates how the three rock types are related to each other and how Earth processes change a rock from one type to another through geologic time.

 

Watch the following video:

https://www.youtube.com/watch?v=6qaG3MqI-4o

 

 

Evaluation

20 - Demonstrated detailed understanding of the concepts related to the types of rocks, how they form and how they fit into the rock cycle. Project is of high quality, creative and neat, and with no spelling mistakes.

15 - Demonstrates good understanding of the concepts related to the types of rocks, how they form and how they fit into the rock cycle. Project is good quality and creative, with only minor spelling mistakes.

10 - Demonstrates some confusion of the concepts related to the types of rocks, how they form and how they fit into the rock cycle with some concepts/information missing. Project is neat but with some spelling mistakes.

5 - Demonstrates a weak understanding of the concepts related to the types of rocks, how they form and how they fit into the rock cycle with major concepts/information missing. Project is messy with many spelling mistakes.

0 - No diagram completed/attempted

 

Conclusion

You have now completed the Rock Cycle Webquest.

 

I hope you have gained valuable information about the different types of rocks and the rock cycle.

 

You can now begin work on your rock cycle diagram.

 

Good Luck!