Transcript WEATHERING TURNING ROCKS INTO SOIL Two types of Weathering  A. Mechanical: physical breakdown of rock into smaller pieces 4 WAYS: 1.

WEATHERING
TURNING ROCKS INTO
SOIL
Two types of Weathering
 A. Mechanical: physical breakdown of rock into smaller pieces
4 WAYS:
1. Exfoliation: repeated heating/cooling –
top layers of rock peels away
2. Frost Action: water seeps into cracks,
freezes, expands – crack widens (ice wedging)
3. Organic Activity: plants & animals
A. burrowing: digging exposes rock
B. root pry: roots widen cracks in rocks
4. Abrasion: rocks hit each other – causing
them to break (wind, running water, gravity)
What happened here?
Another type of weathering: Video Clip
 B. Chemical: a change in rock composition
Happens in 5 ways:
1. Hydrolysis: rocks react with water
2. Carbonation: Carbon dioxide + water =
carbonic acid (limestone caverns)
3. Oxidation: oxygen reacts with metallic
elements (iron & oxygen = rust)
4. Sulfuric Acid: pollution/acid rain
corrodes rock
5. Plant Acids: seep into rock & dissolve
minerals (Lichen seen in video clip)
Rates of Weathering
 Depends on:
A. Composition of rock:
- Sedimentary rock weather faster than igneous/metamorphic
-Minerals present in rock:
* quartz: very hard mineral – weather’s slowly
* calcite: chemical weathering by carbonation
B. Amount of exposure:
-More surface area – increased rate of weathering
-Less surface area – slower rate of weathering
C. Climate:
- lots of rain - hydrolysis
- freezing climate – frost action/ice wedging
Weathering and SOIL
SOIL TYPES
1. Bedrock
Solid rock at
Bottom – “parent rock”
2. Soil
Mix of minerals, water,
gases, dead stuff
Various layer within
3. Humus
Dark organic matter of
decaying stuff
SOIL TEXTURES
GRAVEL SANDY
SILTY
CLAY
Based on particle
sizes present in
sample
The spaces between
the particles is called
PORE SPACE
What type of soil do YOU see?
Gravel
Silt
Clay
Sand
Using the textbook at your desk, complete the following:
Beginning at pg. 432 read each
section and complete the section
reviews for each section.
The section reviews can
be found on pages: 440, 442
and 446.
On Pg. 450: do #’s 1-9 MC; 1-8 T/F and the Concept Map