Port Ewen Formation
Tim Pirolli
The Port Ewen formation, located in various outcrops in New York State, belongs to the Helderberg Group of the Lower Devonian.  Though the exact dates of the strata are very difficult to determine, the Lower Devonian has been dated to be between 415 and 380 million years ago.  The specific Port Ewen outcrops visited on our tour through the Early Devonian of New York State included sites near Catskill Creek (on Route 23), an outcrop near Kaaterskill Creek (on Route 23A) and an outcrop along Route 199 in Kingston.

As for the formation itself, it has been documented to have thicknesses above 100 feet near Kingston, with a maximum thickness of 180 feet recorded further south.  Further north and west, the Port Ewen thins to only 10 feet at a site near Coxsackie.  The Port Ewen is often observed resting on the Alsen formation.  It has also been observed to lie unconformably on the Becraft formation in other outcrops. 
Top: Glenerie-Port Ewen contact boundary on an anticline along route 199 in Kingston, NY.

Bottom: Port Ewen - Alsen contact boundary on an anticline along route 199 in Kingston, NY.

 
The Port Ewen formation corresponds to a deep-water environment off the shore of what is now North America.  During the Devonian, the present-day New York State area was located between 0° and 30° south of the paleoequator.  The actual composition of the formation is an even bedded argillaceous limestone, which contains flecks of chert and clay nodules.  The nodules increase in both size and density from the base to the end of the formation, where they form an almost continuous band.  The nodules often preserve fossils well within them, such as the trace fossils Zoophycos and Chondrites.  The nodules may have formed as a result of early cementation controlled by bioturbulation.  The Port Ewen also has massive faulting throughout the unit as a whole.
The small greenish-brown clay nodules seen in this limestone formation are a common occurrence in the early Port Ewen formation.  Often, they can be found with well-defined fossils within them.  These nodules were recorded on the side of Route 23 near Catskill Creek, NY.
This is an example of a much larger late Port Ewen nodule (with hammer for scale).  The size of the nodules increased from the beginning to the end of the Port Ewen and were preserved well in this rock formation on the side of Old Kings Highway just south of Catskill, NY.

 
The fauna of the Port Ewen includes brachiopods, bryozoans, ostracods, trilobites, crinoids and some sponge spicules near the top of the formation.  Examples of a rugose coral and the brachiopods Strophonella and Leptaena can be seen on this page.
A common feature of the Port Ewen formation, small flecks of chert can be
seen in this rock found on the side of Old Kings Highway just south of
Catskill, NY.

 
This is a rugose coral (with hammer head for scale) in situ in the Port Ewen outcrop on the side of Route 23 near Catskill Creek, NY.
This is a partial specimen of the brachiopod genus Strophonella, found in an outcrop along Route 199 in Kingston, NY.  The range of this genus was brief, Upper Silurian to Lower Devonian.
This is a wonderful specimen of the brachiopod genus Leptaena, also found along Route 199.  The range of this common brachiopod species was a bit longer, from Middle Ordovician to Devonian.

 
Bibliography:

Bordeaux, Yvette.  "Field Trip to the Hudson Valley Region, New York State, Fall 
2001".

Bordeaux, Yvette.  “Testing Bioturbational Ammensalism: A Suite of Qualitative and Quantitative Techniques for Evaluating Potential Infaunal-Epifaunal Interactions and Their Applications to the Lower Devonian of New York State.”  1999.  Pages 70-74. 

Ebert, James R.  “Trip K; Tidal currents, biogenic activity and pycnoclinal fluctuation on a Lower Devonian ramp; Becraft, Alsen and Port Ewen formations, central Hudson Valley.”  Annual Meeting of the New York State Geological Association Field Trip Guidebook.  New York: New York State Geological Survey, 1987. Pages K1-K35.  Found on GeoRefS.

Mazzo, Carl R., Robert G. LaFleur.  “Stratigraphy of the Port Ewen Formation (Lower Devonian), eastern New York.”  Northeastern Geology.  Troy, NY: Rensselaer Polytechnic Institute, 1984.  Volume 6, no. 2.  Pages 71-82.  Found on GeoRefS.

 
A Philly boy by birth, I come from Bucks County to UPenn to eventually become some sort of doctor.  Of course, one of my real passions is vertebrate paleontology, focusing on dinosaurs.  I've had one major fieldwork experience, assisting Peter Dodson in Montana during the summer of 2001.  I intend to double major in Biology and Geology (Paleobiology concentration) with minors in French and Chemistry.  My current major research interest involves studying gene therapy of chronic ischemia in rabbit and rat heart models, which involves a tremendous amount of surgery and molecular biology.  I also write for and edit Penn's only humor magazine, The Punch Bowl.  My only words of wisdom are that "Life  is fun, people!"

Webpage of my Official Hero:  http://www.sas.upenn.edu/~lamanna/
Only place in Philly to see Dinosaur Bones (other than my bedroom): http://www.acnatsci.org/
Harvard University's Museum of Comparative Zoology:  http://www.mcz.harvard.edu/Departments/InvertPaleo/invertebrate_paleontology.htm
Smithsonian Institution's Page for Paleontology:  http://www.nmnh.si.edu/paleo/
Bounce around the Many Paleo Websites from K-Paleo's:  http://members.aol.com/fostrak/kpaleo.htm

 
Home
Map
Geologic History
Bibliography
Links
Earth & Environmental Science at Penn
Geology 205