Sedimentary Rock
• Sedimentary rock is rock that is
formed from the accumulation and
consolidation of sediments (weathered
particles of other rocks).
• Lithification is the process by which
sediments become rock.
– Ex: sandstone, shale, conglomerate
Compression
Compression occurs as the pressure
created by water and overlying
sediments becomes great enough to
force particles of sediment close
together, drive out any water, and
compact the sediments into rock.
A good example is shale.
Shales
Cementation
Cementation occurs as the addition of
minerals, such as silica, lime, or iron
oxide, tends to “glue” rock particles
together to form solid rock.
Examples are sandstone and
conglomerate, which are composed
of particles of sand, pebbles and
small rocks.
Sedimentary Rocks
Conglomerate
Sandstone
Formation by Chemical Process
Some sedimentary rocks form as the
result of chemical processes such as
evaporation and precipitation.
Rocks formed by the evaporation of
water are called evaporites.
Examples are limestone, rock salt and
rock gypsum.
Examples of Sedimentary Rocks
Formed by Chemical Processes
Formation by Biological Processes
• Some sedimentary rocks form as a
result of processes acting on the
remains of once living organisms.
• Coal is formed from the compression
of dead plants.
• Limestone is formed from the
remaining shells of dead sea-life.
Fossils
Sedimentary rocks also form and
contain remains or impressions
of plants and animals. These
impressions are called fossils.
Fossils
More Fossils
3 Kinds of Sedimentary Rocks
Clastic sedimentary rocks form from the
compaction and cementation of fragments
of other rocks.
Chemical sedimentary rocks form from
mineral grains that precipitate out by
evaporation or other chemical action.
Organic sedimentary rocks form from the
remains of plants and animals.
Properties of Sedimentary
Rocks
Rocks may have one or all of these
properties at the same time:
• Discrete layers
• Fragmental particles
• Organic composition
• Range of particle sizes, or
– Predominance of one particle size.
Sedimentary Samples
Metamorphic Rock
• Any kind of rock can become a metamorphic
rock.
• Metamorphic rock is rock produced by
morphism
– Morphism means to change, so these rocks are
formed by the transformation of preexisting rocks
into distinct new rocks.
• Metamorphic rocks form as a result of the
recrystalization of unmelted material under
conditions of extremely high temperature and
pressure over long periods of time.
Classification of Metamorphic Rocks
Texture refers to the appearance and
mineral arrangement of metamorphic
rocks.
Foliated rocks have minerals that
pressure has aligned into layers that are
easy to split.
Banding occurs when there are thin layers
of alternating minerals.
Metamorphic rocks are in many ways
similar to their parent material.
How Does Morphism Occur?
Metamorphic rocks form as a result
of:
– High temperatures
– High pressures
– Combination of both
–BUT without the rock melting in
the process.
Types of Metamorphism
Contact Metamorphism occurs when molten
rock comes in contact with surrounding
rocks.
The heat from the magma alters the rock
in contact with it.
Regional Metamorphism accounts for the
greatest amount of metamorphism and
occurs when large areas of rock are under
intense heat and pressure.
Metamorphism
Metamorphic Rocks
Metamorphic Rocks
What is the Rock
Cycle?
• The rock cycle is a theory
relating to various rock
forming processes of the
common rock types
The Rock Cycle
Rock Cycle Transition Zones
• The process that creates a transition
zone between rock type is contact
metamorphism