Tectonic History of Long Island

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Tectonic History of Long Island
Glenn Richard Stony Brook University
Map from http//people.hofstra.edu/J_B_Bennington
/research/long_island/li.html
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Tectonics
Greek for "builder", tekton - a geologic field of
study that focuses on the structures, such as
folds and faults, within the Earth's crust and
the geologic phenomena that have created these
structures by operating in specific regions.
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New York State Geologic Map
The geologic history of the region that includes
Long Island is recorded in rocks throughout New
York State and New England.
Stony Brook
Published by the University of the State of New
York
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Continued Major Geologic Eventsin New York State
1.1 Billion Years Ago Grenvillian Orogeny
Rodinia (supercontinent) 650 Million years Ago
Rifting of Rodinia Iapetus
Ocean 480 Million years Ago Taconian
Orogeny 400 Million Years Ago Acadian
Orogeny 290 Million Years Ago Alleghenian
Orogeny Pangaea (supercontinent) 250 Million
Years Ago Rifting of Pangaea -gt Atlantic
Ocean 80 Million Years Ago River delta -gt
Fossils now found on North Shore 1.6 Million
Years Ago Start of period of ice advances and
retreats 20,750 Years Ago Last ice sheet
retreats
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Tectonic History of the Long Island Area
Tectonic Events along East Coast of what is now
North America
Relating to, causing, or resulting from
structural deformation of the earth's crust.

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Grenville Orogeny
1.1 Billion Years Ago
Mount Haystack from Mount Marcy in the Adirondacks
The Grenville Orogeny, 1.1 billion years ago,
created a huge mountain range extending along
what is now the east coast on North America down
to Mexico, evidenced by rocks exposed in the
Adirondacks and buried well below the surface of
the remainder of New York State. This event also
formed the Grenville Supercontinent.
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Rifting of Rodinia
650 million years ago
North America
From http//www.scotese.com/precambr.htm
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Diabase dike (650 mya) in western Adirondacks
intruded during breakup of Grenville
supercontinent.
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500 Million Years Ago A Warm Shallow Sea
Ripple marks on Potsdam Sandstone (500 mya),
Ausable Chasm display. Formed in warm shallow
sea. Potsdam sandstone probably covered
Adirondacks and was eroded from central portions
after later uplift.
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Taconian Orogeny
450 million years ago Hartland Island arc
collides with Laurentia North America
Hartland Gneiss
Details
Subduction zone forms in Iapetus OceanHartland
volcanic island arc forms behind subduction
zoneThe oceanic crust between the island arc and
Laurentia subducts until the island arc collides
with Laurentia
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Acadian Orogeny
380 million years ago Avalon collides with
North America
Details
Avalonia splits from Gondwana and becomes
attached to BalticaBaltica included the land
areas now bordering the Baltic SeaThe collision
of Baltica with Laurentia in the Silurian is the
Caledonian OrogenyCaledonian Orogeny progresses
south and becomes the Acadian Orogeny 
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Alleghenian Orogeny
300 million years ago Gondwana collides with
Laurentia North America
Diagram represents a time prior to the collision
Details
Oceanic crust between Avalonia and Gondwana  is
subductedThe collision of Gondwana and Laurentia
is along a transform marginGondwana rotates
clockwise causing more intense uplift in southern
Appalachians
Diagram from http//csmres.jmu.edu/geollab/vageol
/vahist/Allegeve.html
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Pangaea
North America
Europe, Asia
Africa
South America
Australia
Antarctica
300 million to 200 million years ago
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Atlantic Ocean
Rifting of Pangaea began about 200 million years
ago
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BreakupofPangaea
200 Million Years Ago formation of the Atlantic
Ocean
Watchung Ridges
Palisade Sill
From http//3dparks.wr.usgs.gov/nyc/mesozoic/mesoz
oicbasins.htm
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Late Cretaceous
94 million years ago
By Late Cretaceous, extensive river deltas had
formed along east coast of North America
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Maximum Extent of the Most Recent Continental Ice
Sheet(about 20,750 years ago)
FromUnited States Geologic Survey
Mashomack
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Long Island Digital Elevation Map
Note lines of hills in central Long Island and
along North Shore. A smaller, but similar, area
of hills is present on Shelter Island.
Harbor Hill Moraine
Peconic Bay Moraine
Ronkonkoma Moraine
From NEW OBSERVATIONS ON THE GLACIAL
GEOMORPHOLOGY OF LONG ISLAND FROM A DIGITAL
ELEVATION MODEL (DEM) Bennington, J Bret,
geojbb_at_hofstra.edu Department of Geology 114
Hofstra University, Hempstead, NY 11549