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Tectonic History of Long Island. Glenn Richard Mineral Physics Institute Stony Brook University. Map from: http://people.hofstra.edu/J_B_Bennington/research/long_island/li.html. Tectonics:. Greek for "builder", tekton

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tectonic history of long island
Tectonic History of Long Island

Glenn Richard

Mineral Physics Institute

Stony Brook University

Map from: http://people.hofstra.edu/J_B_Bennington/research/long_island/li.html

tectonics
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.

new york state geologic map
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

continued major geologic events in new york state
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 -> Atlantic Ocean

80 Million Years Ago – River delta -> 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

tectonic history of the long island area

Tectonic Events along East Coast of what is now North America

Tectonic* History of the Long Island Area

*Relating to, causing, or resulting from structural deformation of the earth's crust.

grenville orogeny
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.

rifting of rodinia
Rifting of Rodinia

650 million years ago

“North America”

From http://www.scotese.com/precambr.htm

slide8

Diabase dike (650 mya) in western Adirondacks intruded during breakup of Grenville supercontinent.

slide9

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.

taconian orogeny
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

acadian orogeny
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 

alleghenian orogeny
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

pangaea
Pangaea

North America

Europe, Asia

Africa

South America

Australia

Antarctica

300 million to 200 million years ago

atlantic ocean
Atlantic Ocean

Rifting of Pangaea began about 200 million years ago

breakup of pangaea
BreakupofPangaea

200 Million Years Ago – formation of the Atlantic Ocean

Watchung Ridges

Palisade Sill

From http://3dparks.wr.usgs.gov/nyc/mesozoic/mesozoicbasins.htm

late cretaceous
Late Cretaceous

94 million years ago

By Late Cretaceous, extensive river deltas had formed along east coast of North America

maximum extent of the most recent continental ice sheet about 20 750 years ago
Maximum Extent of the Most Recent Continental Ice Sheet(about 20,750 years ago)

FromUnited States Geologic Survey

Mashomack

long island digital elevation map
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@hofstra.edu

Department of Geology 114 Hofstra University, Hempstead, NY 11549