Transcript Sedimentary Rocks

Student
Concept
Map
Sedimentary Rocks
Dr. David Steer
Rock Cycle
Group discussion time
 Given:
 Bag
of sedimentary rocks
Group these rocks in some manner.
Grouping items
 Remember
this exercise?
Grouping items
 Group
these objects in some logical way.
Depositional setting (3)
Texture
Grouping items
 Group
these objects in some logical way.
Throw
Target
Use only
hands
Hit with a stick
Kick
Sedimentary Rocks: Deposition

Clastic (detrital) sedimentary rocks –


Chemical sedimentary rocks


composed of sediments, rock and mineral fragments formed
when rocks disintegrate at or near the earth's surface.
precipitated from a solution (e.g. sea-water) as the result of
changing physical conditions (e.g. evaporation).
Biochemical sedimentary rocks –

formed by the actions of living organisms or composed of the
remains of dead organisms.
Clastic or Detrital Sedimentary Rocks
 Clastic

sediments Classified based on:
coarse grain size particles
 (gravel,
 medium
includes pebbles, cobbles and boulders),
grain size
 (sand)
 fine
grain size
 (silt)
 very
May appear layered
gritty feel of sample
fine sediment
 (clay)
too fine to see
Clastic Rocks Classified
Sediment
Grain Size
(diameter)
Sedimentary
Rocks
Shale, Mudstone
Clay
less than 0.0039 mm
Silt
0.0039 to 0.0625 mm
Siltstone
Sand
0.0625 to 2 mm
Sandstone
Gravel
more than 2 mm
Conglomerate
Review

Which rock is most likely sedimentary?
Temperature when formed
A
B
Depth
C
D
E
Examples of clastic sedimentary rocks

Mudstone

Fine grained low energy
Sandstone
Medium grained moderate
energy
Individual grains visible
in samples
Conglomerate
Medium to coarse grained
high energy
Chemical Sedimentary Rocks
 Chemical
sedimentary rocks –
 precipitated
from a solution (e.g. sea-water) as a result
of changing physical conditions (e.g. evaporation).
 May be difficult to see layers
 Biochemical
 formed
sedimentary rocks –
by the actions of living organisms or composed
of the remains of dead organisms.
 Fossils usually apparent
Examples of Biochemical Sedimentary Rocks

Limestones

form when marine
organisms die and their
skeletons accumulate.
Coal
forms
when land plants
die and their organic
tissue accumulate.
Concept Map
 Construct
a concept map that guides you through
classifying a sedimentary rock.
Classify these rocks.