Book G Chapter 2
Lesson 1 – Review Answers
1. What are the three things that can cause abrasion?
The three processes that cause abrasion include abrasion by wind, water (moving water) and gravity.
2. Fill in the spaces to show the steps in the cycle of ice wedging.
3. How can acids cause chemical weathering?
Acids that come in contact with rocks will react with materials contained in the rock. These chemical reactions will weaken the rock, causing the rock to weather over time. Acids can also dissolve rock material, creating holes and cracks in rocks. Acids can dissolve large areas of rock, creating caves and caverns.
4. How is mechanical weathering caused by ice wedging similar to mechanical weathering caused by plant roots.
Mechanical weathering caused by ice wedging and plant roots cause rocks to ‘break’ from the inside out. Water seeping into rocks will freeze and expand, pushing the rock apart from the inside. Plant roots can slowly grow inside rocks through small holes or cracks. As the plant root grows and becomes larger, the root will slowly push apart the rock from the inside. Both processes involve breaking the rock apart from the inside of the rock.
What is weathering?Weathering is the process by which rock material is broken down over time.
Name the two types of weathering.
1. MECHANICAL / 2. CHEMICALABRASION:
the grinding or wearing away of rock / OXYGEN: OXIDATION
rocks that contain iron go through the process of oxidation
iron atoms in the rock react with oxygen atoms – this is called oxidation
rust is formed from oxidation; rust can weaken the rock, making it brittle and easy to break apart
ICE:
ice can break apart rocks from the inside
happens in climates that have cycles of above and below freezing temperatures
water seeps into rocks, freezes and expands, creating larger spaces inside the rock.
this process continues until the rock breaks apart / ACID PRECIPITATION
acids react with rocks to dissolve the rock material
created from pollution in the air combining with water in the atmosphere
created from natural events like volcanic eruptions
can be in the form of rain, sleet, snow or fog
WATER:
MOVING water can cause rocks to bump and scrape against each other, causing rocks to chip and break apart
rivers, streams, shorelines
rocks appear smooth, rounded and can be small or large / ACID IN LIVING THINGS:
some living organisms produce weak acids
plants like lichens grow on rocks and the roots produce a weak acid
over time, the weak acid reacts with the rock to cause holes, cracks or breaks in the rock
WIND:
wind can pick up small particles of sand, rock and dust
these particles hit rocks, causing the rocks to wear away / WATER:
water is a chemical!
over time, rocks that are in still water (water that is not moving) will slowly dissolve over time
GRAVITY:
rocks that fall down the side of mountains, hills or cliffs (through natural events) will break apart as they roll down and reach the bottom of the mountain, hill or cliff / ACID IN GROUNDWATER:
groundwater is water that moves through the surface crust of Earth
this water can collect in spaces under the ground
the water can become acidic from contact with minerals and other chemicals found naturally in the ground
this water can dissolve rock, especially limestone, and form caves, caverns and other underground rock structures
PLANTS:
the roots of plants can get inside rocks through small holes or cracks in the rock
over time, the roots grow larger and pry apart the rock from the inside out
plants and plant roots can break rock structures if the plants grow through the rocks or the roots can break rocks at the surface if the roots are close to the surface
ANIMALS:
burrowing animals can scrape rocks or move rocks into each other
this natural action can break apart rocks
rabbits, foxes, burrowing insects, worms