Rock Cycle Notes
1. crust of the earth is made mostly of rock and rock fragments
2. rocks are actually a solid mixture of mineral crystals
3. mineral is a solid that has a crystal structure and a specific chemical composition
4. Igneous, sedimentary, and metamorphic rocks are the three main types
5. Rock Cycle-at any given time, a rock can be at any point on the rock cycle and can change from one type of rock to another
6. Igneous rock is formed from the cooling and solidification of magma
7. Rocks composed entirely of large mineral grains cooled slowly below ground and are called intrusive
8. mineral grains are mostly small if the rock is extrusive, that means formed from lava spilled from a volcano eruption
9. Sedimentary rock is formed by the compaction and cementation of sediments
10. sediment- the remains of rocks that have been broken down into small and tiny pieces.
11. Metamorphic rock is formed deep underground due to great heat and pressure on existing rock
Soil, weathering, erosion notes
1. weathering-when a rock is broken down into smaller pieces by wind, water, chemicals, plants, and animals.
2. rocks weather in response to their environments
3. mechanical weathering-process where rocks are physically broken into smaller pieces by wind, water, and ice or heat
4. Grand Canyon is an example of mechanical weathering
5. chemical weathering-minerals within rocks are broken down by removing or changing elements found in those rocks. Carbon dioxide combines with water to form a weak acid
6. biological weathering-when living organisms cause chemical or mechanical weathering
7. plant roots can secrete enzymes that slowly eat into rocks
8. erosion is the movement of soil or rock by water, ice, or wind
9. weathering is the destruction and erosion is the movement
10. gravitational erosion-chunks of rock and even mountainsides sink and/or fall downhill caused by gravity
11. soil formation is a product of weathering
12. soil consists of weathered rock and decomposed organic material
13. humus is the organic material in soil.
14. continued weathering releases minerals that plants need for growth
15. organic material is decaying and rotting plants, releases the minerals that the plant absorbed
16. organic means carbon based, we are carbon based.
17. mature soil is soil that has developed over thousands of years.
18. horizons-mature soil can be divided into three layers called horizons
19. the top or “A” horizon is called the topsoil, where shallow plant roots absorb water and nutrients, also home to insects and worms
20. the second or “B” horizon is the subsoil, where you find clay and minerals and the DEEP roots of plansts
21. the “C” horizon contains the weathered bedrock and is not part of the soil.