ROCKS AND ROCK CYCLES

The Manly assistant lives!

The Rock Cycle“Around and around and around” The rock cycle is the process where new

rock is formed. It can happen by: Melting then cooling (igneous) Heat/pressure (metamorphic) Compaction and cementation (sedimentary)

Any of these rocks can change into any of the other types.

Rock cycle 2 Igneous rock forms from rock melting then

solidifying. How fast it cools determines how big the crystals are.(fast=small slow=big)

The heat needed for this comes from inside the Earth. Any rock can melt and become an igneous rock.

Metamorphic rock happens when the rock is heated and pressurized. Heat and pressure are always required. Complete melting can occur but is not necessary

Rock cycle 3 Bits of rock, sand, or clay can be eroded,

deposited or cemented. They are then compacted to form sedimentary rock.• Erosion changes the shapes of rocks as they

break down.• Over time wind and water can show the

direction of erosion. (like a dune being blown to the west) .

Weathering and Erosion “In time even you will be old and craggy” Weathering and erosion break down rocks

over time, making them smaller and smaller.

Which is why you should never build a house on a cliff. It will erode and your poor house will fall!

If you really want to, you should build a retaining wall to keep rocks from breaking off and eroding the edge of the cliff.

Weathering and Erosion 2

Streams, brooks, and rivers are places where weathering can occur.

Soils forms from weathering - breaking down rocks into smaller and smaller pieces.• Farmers use this knowledge to protect their

plants and soil from erosion.

Fossils“Cough My Grandpa cough”

Fossils are the remains of a once living organism that has been preserved. This can happen in mud or peat (sediments).

The original organism is actually replaced by minerals when it fossilizes. All soft tissues and internal structures disappear!• A fossil leaf is not an actual leaf. It is actually

an impression in sedimentary material that preserved its shape.