Formation of Sedimentary

Rock!Forces of Erosion

andTypes of Weathering

Sedimentary Rock Formation

(Exploring Earth: Visualizations – How sediments are deposited)

• Sedimentary Rock Formation Clip!

WeatheringThe Process of breaking down rocks

and minerals into small pieces.

• Mechanical Weathering – breaks rocks into smaller pieces but does not change the chemical composition of the rock.o Temperature Changeso Freezing Watero Root Actiono Animal Activityo Abrasion from water/windo Exfoliation/Release of pressure

Types of WeatheringPhysical/Mechanical – Temperature

Changes!• Heat makes most things expand, while cool

makes most things contract. Temperature changes during the day and night cause rocks to crack over time

Types of WeatheringPhysical/Mechanical – Freezing Water!• Water expands when it freezes. So, water

in the cracks of rocks expands and cracks the rock more when it freezes.

Water can penetrate into cracks and when it freezes the water expands. The rock cracks a little more each time this happens.

Types of WeatheringPhysical/Mechanical – Root Action!• Trees and shrub have roots that can grow

into cracks of rocks. Growing roots are very strong and can split rocks.

Types of WeatheringPhysical/Mechanical – Animal Action!• Animals don’t break rocks by digging. But,

they dig into the ground allowing both air and water to cause weathering of rocks under the ground.

Types of WeatheringPhysical/Mechanical – Abrasion from running water/wind

• Both wind and water can act like sandpaper and cause physical weathering of rock.

Types of WeatheringPhysical/Mechanical – Exfoliation/Pressure Release

• A process where the outer layer of rock peels away. Rock underneath experience a decrease in pressure and expands causing more cracking.

Weathering• Chemical Weathering - breaks rocks into smaller

pieces and changes the chemical composition of the rock.o Oxygen (oxidation)o Watero Carbon Dioxide

Types of WeatheringChemical – Carbon Dioxide!• CO2 combines with rain water to form

Carbonic Acid (or acid rain). This “acid rain” can dissolve some types of rock such as limestone.

Types of WeatheringChemical – Water!Water can change minerals in 2 ways. 1. It dissolves some minerals out of rocks

making them brittle and easily broken.2. Water combines with other substances to

form new molecules and can easily break away from the rock.

Types of WeatheringChemical – Oxygen!• Oxygen can combine with other minerals to

form oxides. The rock is now chemically changed and can break away from the original rock.

Rust!

Erosion• The process of moving rocks

and minerals.o Windo Watero Ice

Forces of ErosionWIND!• Wind can smooth and break rocks into

smaller pieces and can move them to be deposited in another place.

Forces of ErosionWater!• Water can smooth and break rocks into

smaller pieces and can move them to be deposited in another place.

Forces of ErosionGlaciers!• Large ice masses can smooth and break

rocks into smaller pieces and move them to be deposited in another place when the ice melts.

Weathering and Erosion

• Weathering breaks rocks into _________ and those _________ are carried away by the processes of ______.

• ________can be cemented or compacted over time to form this type of rock. _________________________

sediments sediments

erosion

Sediments

Sedimentary Rock