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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Mineral Physics Institute
Stony Brook University
Map from: http://people.hofstra.edu/J_B_Bennington/research/long_island/li.html
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.
The geologic history of the region that includes Long Island is recorded in rocks throughout New York State and New England.
Published by the University of the State of New York
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
*Relating to, causing, or resulting from structural deformation of the earth's crust.
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.
650 million years ago
Diabase dike (650 mya) in western Adirondacks intruded during breakup of Grenville supercontinent.
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.
450 million years ago – Hartland Island arc collides with Laurentia “North America”
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
380 million years ago – Avalon collides with North America
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
300 million years ago – Gondwana collides with Laurentia “North America”
Diagram represents a time prior to the collision
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
300 million to 200 million years ago
Rifting of Pangaea began about 200 million years ago
200 Million Years Ago – formation of the Atlantic Ocean
94 million years ago
By Late Cretaceous, extensive river deltas had formed along east coast of North America
FromUnited States Geologic Survey
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
NEW OBSERVATIONS ON THE GLACIAL GEOMORPHOLOGY OF LONG ISLAND FROM A DIGITAL ELEVATION MODEL (DEM)
Bennington, J Bret, email@example.com
Department of Geology 114 Hofstra University, Hempstead, NY 11549