Department of Geology

Research and Education
Long Island Geology

Dr. J Bret
Bennington
 

Digital Elevation Models
Glacial Geology
Cretaceous Geology
Coastal Processes and Features

Digital Elevation Models, Long Island, NY

DEM Maps are produced from digital elevation data consisting of files of grid-referenced geographic points with elevation values. DEM data can be downloaded from several sources on the internet and visualized using a variety of shareware and commercial software applications. DEM maps are color coded to show elevation gradients and are usually shaded to make topographic features stand out.


Why is the western tip of Brooklyn missing from these maps? There is an error in the data file for the Narrows quadrangle that prevents me from incorporating it into the DEM.

Digital elevation model of Long Island, New York

DEM of Long Island with elevation key. Click on image for larger web version (124 kb).

Download full size version of this image (111" by 52", 72 dpi, 2.8 mb jpg).

Download pan and zoom QTVR movie of this image (824 kb - requires Quicktime Player)


DEM map of Long Island region

DEM of Long Island and surrounding region. Click on image for larger version (360 kb).

This map was made using data downloaded from the USGS The National Map Seamless Data Distribution System.


DEM map of Long Island - Gil Hansen

DEM of Long Island by Dr. Gil Hansen. Click on image for larger web version (124 kb).

Download full size version of this image (182" by 40", 100 dpi, 8.1 mb jpg).

Download pan and zoom QTVR movie of this image (4.1 mb - requires Quicktime Player)


Interested in making your own DEM maps? Check out these links:

Sources of DEM data files:
Cornell University Geospatial Information Repository (CUGIR) - NY maps
New York State GIS Clearinghouse - NY maps
USGS The National Map Seamless Data Distribution System - National / International

DEM viewing software:
MicroDEM (PC viewing program by Dr. Peter Guth, USNA)
MacDEM (Mac viewing program by Jerry Farm)

Information about DEM maps:
Technical info from the USGS


Glacial Geology
All of Long Island is the product of the advance and retreat of glacial ice sheets and topographic features related to the movement and melting of glacial ice can be seen in many places. The north shore of Long Island exposes glacial till and outwash, as well as glacial boulders (erratics), hills constructed from moraines and kames, depressions formed as kettles, and valleys carved by subglacial meltwater. These features are easily seen in the Huntington-Northport area and at Caumsett State Park on Lloyds Neck.

The contact between the upper gently dipping Pleistocene outwash gravels and the lower Cretaceous sands is visible as an orange band in the center of the cliff face.

QTVR panorama of the sediments exposed in the cliffs near the fishing access at the west end of Caumsett State Park (1.3 mb).

Requires Quicktime Player


Most of the sediments visible in this panorama are Cretaceous sands. Some Pleistocene sediments are visible near the top of the exposure.

QTVR panorama of the sediments exposed in the cliffs east of the previous panorama (1.3 mb).

Requires Quicktime Player


Sediments exposed in this panorama are predominantly Pleistocene tills.

QTVR panorama of the sediments exposed in the cliffs near the east end of Caumsett State Park (1.3 mb).

Requires Quicktime Player


360° view of terminal moraine ridge and foot of outwash plain.

QTVR panorama of Harbor Hills moraine at Veterans Memorial Park along Bellerose Ave in East Northport (1.7 mb).

Requires Quicktime Player


360° view of large kettle depression.

QTVR panorama of Ingrahams Nature Preserve in Northport (3.9 mb).

Requires Quicktime Player


View of developed former sand mine in foreground, Northport Bay, Ashroken tombolo, and Eatons Neck in background.

QTVR panorama of Steers Pit overlook, Northport (332 kb).

Requires Quicktime Player

For more information about the sediment layers exposed at Caumsett State Park:

Cliffs and Beach walk at Caumsett State Park by Gloria Mandell
Research report on Cliffs at Caumsett State Park by Gloria Mandell
Field activities for high school students at Caumsett by Jane Tofel.

Bennington, J Bret, and Hakimian, Adina, 2002. Grain-size analysis of Cretaceous and Pleistocene sedimentary facies exposed at Caumsett State Park, Lloyd Neck, New York. Long Island Geologists Conference, Stony Brook, New York, April 2002.

Photos of Cretaceous plant fossils found along the shore of Lloyd Neck, Long Island.

For more information about the glacial features of Long Island:

Evaluation of Geomorphology of the Stony Brook-Setauket-Port Jefferson Area Based on Digital Elevation Models by Dr. Gil Hanson, SUNY Stony Brook

"Glacial Features of the Huntington and Northport Area, Long Island" Field trip guide and road log by Dr. Bret Bennington (Download as MS Word document.)

Bennington, J Bret, 2003. New Observations on the Glacial Geomorphology of Long Island from a digital elevation model (DEM). Long Island Geologists Conference, Stony Brook, New York, April 2003.

Bennington, J Bret and Young, Tim, 2005. Determining the direction of ice advance forming the Roanoke Point Moraine from a survey of Hartford Basin erratics. Long Island Geologists Conference, Stony Brook, New York, April 2005.


Cretaceous Geology
Long Island's glacial sediments and landscape are underlain by gently dipping coastal plain deposits of Late Cretaceous age. These deposits are typically buried and below sea level under much of the island, however, there are exposures of Cretaceous sands and clays exposed in the beach cliffs along the western north shore. Most, if not all, of these outcrops of Cretaceous sediment are out of place, having been ice-thrusted by the advance of glacial ice and incorporated into the moraine deposits along the north coast of Long Island.

Photos of Cretaceous plant fossils found along the shore of Lloyd Neck, Long Island.

Publications related to this topic also include:
Bennington, J Bret
and Durso, Greg, 1999. The Cretaceous Flora of Long Island. American Paleontologist 7(4):2-4.


Coastal Processes and Features

Wolff, M.P. and Bennington, J Bret, 2000. A comparison of changes between natural and re-nourished beaches ­ the 1997-2000 interval between sand replenishment at eastern Jones Beach Island and western Fire Island, New York. Long Island Geologists Conference, Stony Brook, New York, April 2000.

Beach profile animations for Jones Beach and Fire Island, NY

Annotated slide presentation of Southampton Beach walk conducted by Dr. Steve Leatherman at NYSMEA Conference in 2001. Download as PowerPoint file (5.5 mb)


Last modified 4-18-05 by Bret Bennington. All rights reserved by the author. This document may not be distributed or posted in any format or reposted on any other server without permission.
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