Transcript 3.3 Sedimentary Rocks

AIM: How are Sedimentary Rocks
Formed?
Do Now: Take out your ESRT and turn to page 7.
Look at the chart called Scheme for Sedimentary
Rock identification and answer the questions
below.
1) What textures of Sedimentary rocks will we be
working with?
2) What material (not composition) are Clastic
rocks made from?
I. Formation of Sedimentary Rocks
- mostly made from pieces of other rocks
(as well as once living things and
precipitates)
- Sediment is small pieces of rock
Bioclastic Limestone
Rock salt
Conglomerate
II. How are Sedimentary rocks made?
What material do you need to make most Sedimentary
Rocks?
• Weathering - the breaking down of rocks
into little pieces (sediment)
• Erosion
- the transport of sediment
by water, wind or ice
(agents of erosion).
• Deposition - When the sediment stops
moving. They stop because
the agent of erosion stops.
• Compaction and Cementation (Lithification)
– squeezes and glues sediments together
forming a rock.
– Pressure of overlying material squeezes
– Minerals dissolved in water act as glue
Sediments
are
lithified into
clastic
sedimentary
rock
III. Classification of Sedimentary Rocks
A. Clastic (fragmental) – composed of
weathered bits of rocks.
- Categorized by particle (grain) size.
Siltstone (silt)
Sandstone (sand)
Conglomerate and Breccia (Pebbles)
Shale (clay)
B. Crystalline (Chemical) (precipitates)–
- water evaporates and leaves material
behind to form rocks.
- rocks have a milky or crystalline
appearance
Limestone
Rock salt
C. Bioclastic
- composed of once living things (plants and
shells).
Limestone
Limestone
Bituminous Coal
Take a black cup of rocks from the back of the
room
IV. Features of Sedimentary Rocks
1. Layers – continuous depositions of
sediments causes a layering effect. (like
sand art)
2. Fossils – imprints of ancient life.