GEOL 11: PRINCIPLES OF GEOLOGY 2nd Year
1st Sem
LESSON 11: Sedimentary Rocks and Processes S.Y 2023 - 2024
-Physical (or mechanical) weathering
Sedimentary Rocks ● Rocks are broken down into pieces due to
physical forces / stresses, without
-It is composed of sediments — either detrital
undergoing compositional change
(rock and mineral fragments) or biochemical (or
● Promotes further weathering by increasing
bioclastic — e.g. shells and plant material) — that
the surface area available for physical
undergo lithification (transformation of loose
forces and chemical reactions to act on
sediments into solid rock) by compaction and
cementation
-It is composed of minerals that form in situ (by
precipitation from a solution) and accumulate and
bind into a chemical sedimentary rock
-Examples of Common descriptions of
Sedimentary rocks
● Bedded
● Clastic
● Prevails in high altitudes, dry regions, cold
● Muddy
climates
● Sandy
● The ratio of surface area-to-volume
● Gravelly
increases when a particle decreases in
size, all things being equal. As such, as a
importance of Sedimentary Rocks rock is weathered away into finer
particles, more surface area is available
-Sedimentary rocks serve as record of the earth’s
for the weathering process to act on.
geological history
● The same conc
-Sedimentary rocks serve as host for many
mineral and energy resources
Sedimentary Processes
-Refers to all processes that shape a sedimentary
rock — from the sediment source to its formation ept
and modification explains why modern insects are generally
smaller than other animals. Insects
Erosion breathe by diffusion of oxygen through
-The process by which soil, and mineral and rock holes (spiracles) in its exoskeleton. As such,
particles are worn away (weathering) and moved there is a point when an insect becomes so
elsewhere by gravity, or by a moving transport big that diffusion alone (related to the
agent – wind, water or ice (transportation) surface area of the exoskeleton) cannot
-Agents of Erosion supply the oxygen needed to sustain it. On
● Water the other hand, insects in the
● Gravity (mass wasting) Carboniferous – Permian are bigger
● Wind because the oxygen concentration in the
● Organism atmosphere is much higher than today
● Ice (31-35% then instead of today’s 21%).
-Weathering ● Frost Wedging
● Either by physical (or mechanical) or ○ Occurs due to stresses induced by
chemical means the expansion of ice when water
, GEOL 11: PRINCIPLES OF GEOLOGY 2nd Year
1st Sem
LESSON 11: Sedimentary Rocks and Processes S.Y 2023 - 2024
trapped in existing joints and ○ The kinetic energy of flowing water
fractures freezes alone, without suspended
○ Forms talus deposits downslope of sediments, may be enough to
bare rock surfaces erode rocks and sediments in a
○ Water expands about 9% in volume stream bed (evorsion), as in
when it freezes, because the water waterfall pools, although the effect
molecules crystallize into a is enhanced by abrasion
hexagonal lattice structure ○ The impact of ocean waves may
also break rocks, especially when
cavitation occurs
○ Cavitation as a mode of coastal
erosion occurs when air bubbles in
an incoming wave are forced into
cracks in the cliff being eroded.
Varying pressure decompresses
some vapor pockets, which
○ The background image shows talus subsequently implode. The
deposits near Prohibition Creek in resulting pressure peaks can blast
Canada. Frost wedging from the apart fractions of the rock
upper cliffs supply material to form ● Heating and Cooling (Insolation
the talus deposits below Weathering)
● Exfoliation due to unloading ○ Repeated expansion and
○ When overlying material is contraction due to rapid
removed, previously buried rock temperature changes may cause
masses, which were subjected the formation of joints and
under compressive stresses may fractures
expand due to the removal of ● Wetting and Drying
loading pressure ○ Fractures may also form from
○ The expansion results into repeated expansion and
exfoliation (also sheeting, or onion contraction of materials due to
weathering), wherein material is wetting and drying
shed superficially as scales or ○ Common in clay-bearing rocks and
layers soils
○ Exfoliation is a common -Chemical Weathering
occurrence in batholiths ● Rocks are broken down into pieces by
● Abrasion chemical reactions
○ The mechanical wearing down, ● Chemical weathering attacks less stable
scraping, or grinding away of a minerals by leaching or alteration to more
rock surface by friction, resulting stable minerals
from the action of running water or ● Prevails in warm and humid climates
waves, wind, and ice. Entrained ● Dissolution
particles enhance the effect ○ Breakdown of minerals into ions
abrasion, especially in the case of ○ Dominant process in evaporites
wind (sandblasting) and limestones
● Weathering by Impact ● Hydrolysis
○ Impacts may also cause a rock to ○ Common for silicate minerals,
break, as in rock falls and where hydrogen (H+) and hydroxyl
landslides
1st Sem
LESSON 11: Sedimentary Rocks and Processes S.Y 2023 - 2024
-Physical (or mechanical) weathering
Sedimentary Rocks ● Rocks are broken down into pieces due to
physical forces / stresses, without
-It is composed of sediments — either detrital
undergoing compositional change
(rock and mineral fragments) or biochemical (or
● Promotes further weathering by increasing
bioclastic — e.g. shells and plant material) — that
the surface area available for physical
undergo lithification (transformation of loose
forces and chemical reactions to act on
sediments into solid rock) by compaction and
cementation
-It is composed of minerals that form in situ (by
precipitation from a solution) and accumulate and
bind into a chemical sedimentary rock
-Examples of Common descriptions of
Sedimentary rocks
● Bedded
● Clastic
● Prevails in high altitudes, dry regions, cold
● Muddy
climates
● Sandy
● The ratio of surface area-to-volume
● Gravelly
increases when a particle decreases in
size, all things being equal. As such, as a
importance of Sedimentary Rocks rock is weathered away into finer
particles, more surface area is available
-Sedimentary rocks serve as record of the earth’s
for the weathering process to act on.
geological history
● The same conc
-Sedimentary rocks serve as host for many
mineral and energy resources
Sedimentary Processes
-Refers to all processes that shape a sedimentary
rock — from the sediment source to its formation ept
and modification explains why modern insects are generally
smaller than other animals. Insects
Erosion breathe by diffusion of oxygen through
-The process by which soil, and mineral and rock holes (spiracles) in its exoskeleton. As such,
particles are worn away (weathering) and moved there is a point when an insect becomes so
elsewhere by gravity, or by a moving transport big that diffusion alone (related to the
agent – wind, water or ice (transportation) surface area of the exoskeleton) cannot
-Agents of Erosion supply the oxygen needed to sustain it. On
● Water the other hand, insects in the
● Gravity (mass wasting) Carboniferous – Permian are bigger
● Wind because the oxygen concentration in the
● Organism atmosphere is much higher than today
● Ice (31-35% then instead of today’s 21%).
-Weathering ● Frost Wedging
● Either by physical (or mechanical) or ○ Occurs due to stresses induced by
chemical means the expansion of ice when water
, GEOL 11: PRINCIPLES OF GEOLOGY 2nd Year
1st Sem
LESSON 11: Sedimentary Rocks and Processes S.Y 2023 - 2024
trapped in existing joints and ○ The kinetic energy of flowing water
fractures freezes alone, without suspended
○ Forms talus deposits downslope of sediments, may be enough to
bare rock surfaces erode rocks and sediments in a
○ Water expands about 9% in volume stream bed (evorsion), as in
when it freezes, because the water waterfall pools, although the effect
molecules crystallize into a is enhanced by abrasion
hexagonal lattice structure ○ The impact of ocean waves may
also break rocks, especially when
cavitation occurs
○ Cavitation as a mode of coastal
erosion occurs when air bubbles in
an incoming wave are forced into
cracks in the cliff being eroded.
Varying pressure decompresses
some vapor pockets, which
○ The background image shows talus subsequently implode. The
deposits near Prohibition Creek in resulting pressure peaks can blast
Canada. Frost wedging from the apart fractions of the rock
upper cliffs supply material to form ● Heating and Cooling (Insolation
the talus deposits below Weathering)
● Exfoliation due to unloading ○ Repeated expansion and
○ When overlying material is contraction due to rapid
removed, previously buried rock temperature changes may cause
masses, which were subjected the formation of joints and
under compressive stresses may fractures
expand due to the removal of ● Wetting and Drying
loading pressure ○ Fractures may also form from
○ The expansion results into repeated expansion and
exfoliation (also sheeting, or onion contraction of materials due to
weathering), wherein material is wetting and drying
shed superficially as scales or ○ Common in clay-bearing rocks and
layers soils
○ Exfoliation is a common -Chemical Weathering
occurrence in batholiths ● Rocks are broken down into pieces by
● Abrasion chemical reactions
○ The mechanical wearing down, ● Chemical weathering attacks less stable
scraping, or grinding away of a minerals by leaching or alteration to more
rock surface by friction, resulting stable minerals
from the action of running water or ● Prevails in warm and humid climates
waves, wind, and ice. Entrained ● Dissolution
particles enhance the effect ○ Breakdown of minerals into ions
abrasion, especially in the case of ○ Dominant process in evaporites
wind (sandblasting) and limestones
● Weathering by Impact ● Hydrolysis
○ Impacts may also cause a rock to ○ Common for silicate minerals,
break, as in rock falls and where hydrogen (H+) and hydroxyl
landslides
