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Connecticut’s Geological
History
Marble &
Quartzite
Simplified Geology of Connecticut
Schist
Schist
Gneiss
Sandstone
& Basalt
http://www.wesleyan.edu/ctgeology/CtLandscapes/RalphsSlide25.jpg
Which type of rock is NOT likely to
be naturally found in Avon, CT?
1)
2)
3)
4)
5)
Schist
Basalt
Marble
Sandstone
All of these are likely to be in Avon, CT
Which type of rock is NOT likely to
be naturally found in Avon, CT?
1)
2)
3)
4)
5)
Schist
Basalt
Marble
Sandstone
All of these are likely to be in Avon, CT
Given the CT geology map info, which of
the following statements is accurate?
1) CT is mostly composed of sedimentary rock.
2) CT was never located near a major plate
boundary.
3) All of the rock of CT formed at the same time.
4) CT experienced a shield volcano lava flow.
5) None of these are accurate.
Given the CT geology map info, which of
the following statements is accurate?
1) CT is mostly composed of sedimentary rock.
2) CT was never located near a major plate
boundary.
3) All of the rock of CT formed at the same time.
4) CT experienced a shield volcano lava flow.
5) None of these are accurate.
The oldest rocks in CT are located in the
section called ‘Proto North America’ (PNA).
Given the rocks in PNA today, what rocks were
present prior to their metamorphism?
1) Sandstone and Basalt
2) Granite and Limestone
3) Granite and Basalt
4) Limestone and Sandstone
The oldest rocks in CT are located in the
section called ‘Proto North America’ (PNA).
Given the rocks in PNA today, what rocks were
present prior to their metamorphism?
1) Sandstone and Basalt
2) Granite and Limestone
3) Granite and Basalt
4) Limestone and Sandstone
Which of the following best explains how the
parent rocks in PNA formed?
1)
2)
3)
4)
5)
It was a glacial lake
It was a beach
It had fast moving rivers
It was magma that cooled underground
None of these are reasonable
Which of the following best explains how the
parent rocks in PNA formed?
1)
2)
3)
4)
5)
It was a glacial lake
It was a beach
It had fast moving rivers
It was magma that cooled underground
None of these are reasonable
• Ocean waves wash the
sands from rivers together to
form a beach coastline. This
allows the sandstone to form
over time.
• The marine coastal
environment is where many
shellfish live and die. When
they die, the shells collect at
the bottom and form into
limestone.
There are two sections of ‘Iapetos’ in CT.
Both have the same rock type and origin.
Which of the following best describes that origin?
1) They were ocean crust and marine sediments that
were crunched together in a convergent plate
boundary
2) They were formed by large lava flows
3) They were mountains that wore down into sediments
that later compacted and cemented together.
4) They were formed by a transform plate boundary
There are two sections of ‘Iapetos’ in CT.
Both have the same rock type and origin.
Which of the following best describes that origin?
1) They were ocean crust and marine sediments that
were crunched together in a convergent plate
boundary
2) They were formed by large lava flows
3) They were mountains that wore down into sediments
that later compacted and cemented together.
4) They were formed by a transform plate boundary
The rocks of ‘Avalonia’ used to be
an Island arc off the coast of Africa.
What rock type were they made up of before they
went through metamorphism?
1) Basalt
2) Sandstone
3) Quartzite
4) Granite
The rocks of ‘Avalonia’ used to be
an Island arc off the coast of Africa.
What rock type were they made up of before they
went through metamorphism?
1) Basalt
2) Sandstone
3) Quartzite
4) Granite
Given that Avalonia was composed of
Granite, what does it tell us about its origin?
1) It was likely a subduction volcano island group
2) It was likely a divergent plate volcano island
group
3) It formed by continent-continent convergence
4) It formed because of transform plates
Given that Avalonia was composed of
Granite, what does it tell us about its origin?
1) It was likely a subduction volcano island group
2) It was likely a divergent plate volcano island
group
3) It formed by continent-continent convergence
4) It formed because of transform plates
http://www.wesleyan.edu/ctgeology/CtLandscapes/RalphsSlide12.jpg
What caused the rocks in PNA, Iapetos &
Avalonia to go through Metamorphism?
1) North America collided with Africa forming
Pangaea
2) The rocks were buried by sediments overtime
which caused them to change
3) The rocks were all changed by weathering and
erosion over time
What caused the rocks in PNA, Iapetos &
Avalonia to go through Metamorphism?
1) North America collided with Africa forming
Pangaea
2) The rocks were buried by sediments overtime
which caused them to change
3) The rocks were all changed by weathering and
erosion over time
Why didn’t the rocks in the Newark
Terrane go through Metamorphism?
1) It is made up of rocks that are resistant to acid
weathering
2) It is made up of rocks that are very strong and
resisted the continent collision.
3) The rocks did not form until after Pangaea.
4) The rocks did not form until after the last ice age.
Why didn’t the rocks in the Newark
Terrane go through Metamorphism?
1) It is made up of rocks that are resistant to acid
weathering
2) It is made up of rocks that are very strong and
resisted the continent collision.
3) The rocks did not form until after Pangaea.
4) The rocks did not form until after the last ice age.
http://www.wesleyan.edu/ctgeology/CtLandscapes/RalphsSlide13.jpg
How did Pangaea break up?
1) The drummer died of a drug
overdose and the rest of the band
members went their separate ways
2) Transform Plates
3) Convergent Plates
4) Divergent Plates
How did Pangaea break up?
1) The drummer died of a drug
overdose and the rest of the band
members went their separate ways
2) Transform Plates
3) Convergent Plates
4) Divergent Plates
When Pangaea split up, it did so at a
divergent plate boundary. When plates
begin to diverge, it is not always in a neat
line (think of it more like cracking and
breaking an egg)
The main boundary formed where the
Atlantic Ocean is today. But one of the side
cracks in the initially forming boundary
happened in which part of CT?
1) PNA
2) Iapetos
3) Avalonia
The main boundary formed where the
Atlantic Ocean is today. But one of the side
cracks in the initially forming boundary
happened in which part of CT?
1) PNA
2) Iapetos
3) Avalonia
http://www.wesleyan.edu/ctgeology/CtLandscapes/RalphsSlide19.jpg
http://www.wesleyan.edu/ctgeology/CtLandscapes/RalphsSlide21.jpg
http://www.wesleyan.edu/ctgeology/CtLandscapes/RalphsSlide14.jpg
http://www.wesleyan.edu/ctgeology/CtLandscapes/RalphsSlide15.jpg
But why does the Newark Terrane have
features like Talcott Mountain
(large cliff to the west and a gradual slope
to the east)?
1) It experienced a major fault on the western side
which cause the west to drop down and the east
to rise up
2) It experienced a major fault on the eastern side
which cause the east to drop down and the west
to rise up
But why does the Newark Terrane have
features like Talcott Mountain
(large cliff to the west and a gradual slope
to the east)?
1) It experienced a major fault on the western side
which cause the west to drop down and the east
to rise up
2) It experienced a major fault on the eastern side
which cause the east to drop down and the west
to rise up
Farmers have noticed that the soil in CT is rather
rocky. In the 1800’s many farmers would dig out
the rocks from their fields and use them to make
stone walls around their land.
This was possible due to…
1) Weathering of the sandstone
2) Deposition of glacial till
3) Metamorphism of the ocean rock
4) Deposition of glacial lake sediments
The geological history of CT in 4 Steps (in
Sequence from oldest to most recent) is…
1)
2)
3)
4)
5)
Crack, Crunch, Tilt, Scrape
Crunch, Tilt, Scrape, Crack
Crunch, Scrape, Tilt, Crack
Crunch, Crack, Tilt, Scrape
None of these
CT’s Geologic History
1) Crunch—Pangaea formed
2) Crack—Divergent plate boundary began to
form in the middle of CT. This was followed
by sediments eroding off of the higher
elevation points to the east and west.
3) Tilt—The eastern border fault caused the
eastern half of the Newark Terrane to sink
down.
4) Scrape—Glaciers modified the surface rock
and then deposited sediments as they melt