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Transcript
Plate Movements, Continents and
Connecticut: A Guide to Big Ideas
Why is Connecticut so Amazing?
• Connecticut shows
evidence of various
earth processes,
such as continental
collisions, rifting,
and folding that
have shaped its
structure.
Once Upon A Time
• Some time over 1 billion years ago, there was
an ancient land mass called “Proto- North
America”
• Proto North America eventually became the
North American continent.
• About 1 billion years ago, another continent
collided with proto-North America.
A Big CRUNCH
• Sediments (rock pieces) were caught in
between and pushed up onto North America.
• The collision crumpled the crust, creating
a tall mountain range that stretched from
Canada to Mexico: the Grenville
Mountains.
• These mountains are the earliest evidence
of mountain building in our region, and
Where Did They Go?
•Over time, the Grenville Mountains eroded.
• Rocks remaining from
that ancient mountain
chain are the oldest
rocks that we see
exposed at the
surface in the
Northeast today.
Oh No…Not Again!
• Sometime about 470 million years ago, the
ancient Iapetus Ocean began to close as the
plate carrying Baltica (proto-Europe)
approached the North American plate
• Baltica did not collide
with North America
until several million
years later, but the
convergence of the
two plates created a
whole new look for
eastern North
America.
• As the continents approached one another, the
oceanic crust in the middle was forced under
the Baltica plate.
• The friction and melting of the crust from the
intense pressure of the colliding plates created
a string of volcanic islands along the area
where the plates converged (known as the
subduction zone).
• Over millions of
years, more and more
land was added on
during collisions.
Mountains were built
up on the east coast
of North America.
• More land continued
to add on to North
America over time
Chatfield Hollow: Gneiss Rocks Form
It metamorphoses then uplifts
Pangaea Forms
• Africa collides with North
America between 360 - 245
million years ago
• Pangaea forms a
supercontinent!!!
These collisions resulted in the formation of the
supercontinent of Pangaea. Mountain chains form.
Pangaea begins to rift apart
Pangaea Rifts Apart
By around 200
million years ago,
rifted apart and set
the stage for the
development of
Africa, North
America, and the
Atlantic Ocean as
we know them
Breaking Up is Hard to do…
• Pangaea breaks up!
• Africa pulls away from North America
• Rifts form and fill with sediment and lava
Hills and Valleys
• After the
crunching and
pulling of
continents,
Connecticut
had northsouth ridges
and valleys.
What happened to New England?
Volcanoes forced out great flows of
lava through long cracks in the floor
of the Connecticut Valley.
Tying it all together
The Big Question: What Changed
the Surface of the Earth After This?