t ypes of w eathering. w eathering versus e rosion weathering –rocks and minerals breaking down at...
TRANSCRIPT
TYPES OF WEATHERING
WEATHERING VERSUS EROSIONWeathering –rocks and minerals breaking down at or near the Earth’s surface
Mechanical weatheringChemical weathering
Erosion –moving water, wind, or ice carrying away pieces of rock and soil
Streams, rivers, glaciers, wind and/or waves carry sediment (loose, fragmented surface material that makes up many sedimentary rocks)
WEATHERINGPositiveBreaks down minerals to become part of soils and waterEnriches foods (plants, etc.) and water with essential nutrientsProduces soil, so we can grow crops, etc.NegativeCan weaken building, roads, etcCan destroy monuments, grave markers, etc.
READING ARTICLE
With your shoulder partner, read the article and as you read, think about how the two types of weathering are different or similar.
TYPES OF WEATHERING
Mechanical Weathering –rocks are broken into smaller pieces without changing the chemical makeup of the individual pieces
Examples: Frost wedging, thermal expansion, abrasion, tree root
Chemical Weathering –rocks and minerals that are decompose and are chemically changed
Examples: oxidization, dissolving
ICE WEDGING
Water seeping into cracks in rocks. The water freezes, expands and makes the crack bigger.
Occurs in cold, moist mountain climates
WATER EXPANDS ~9% WHEN IT FREEZES, WEDGING OPEN WATER-FILLED CRACKS IN ROCKS & ROADS!
ABRASION
Rocks fall and collide into one another, breaking off pieces and fragments of rock.
Occurs in cold, wet climates and near glaciers
TREE ROOTS
As tree roots grow, they expand and push apart the rock.
Occurs in warm, moist climates with dense
forests.
PLANT ROOTS CAUSE MECHANICAL WEATHERING
Plants (trees and grasses) are agents of weathering
THERMAL EXPANSION Over time, daily temperature changes cause rocks to break
apart.
Occurs in desert climates with wide ranges in morning and evening temperatures.