Paleoenvironments 3
Eurypterus laculatus
AT LEFT: Upon excavating an area of the quarry floor, in beds of the  Ellicott Creek Breccia Member of the Fiddlers Green Formation, I exposed a series of stromatolite mounds (they are the black masses in the photo to the left).  In the intermound areas of fine-grained dolostone (waterlime), I discovered a fine specimen of this eurypterid. This specimen was col- lected during the Summer of 1985 at the Neid Road Quarry near LeRoy, New York. Note the conchoidal fracturing of the waterlime - it is difficult to reveal a single bedding plane due to this type of fracturing.
AT RIGHT: Enlarged view of this eurypterid specimen. The waterlime here is often under water and becomes covered with algae and sediment that stains the rock.  This specimen is exceptional in being clean, and free of dark material that often obscures bedding planes. Eurypterus laculatus has a very wide geographic distribution, occurring in the Fiddlers Green Formation from near Deck (in Eastern New York) to Haggersville (in Ontario, Canada). Ubiquitous dark blotches that occur on bedding planes are interpreted to be clasts of algae, perhaps ripped off of the associated stromatolites.
AT LEFT: Two views, looking down on  large slabs of Phelps Waterlime, Fiddlers Green Formation, Bertie Group.  The 'lumpy' surface is due to the stromatolitic nature of this water- lime.  Very shallow deposition is indicated not only by the thinness of the slabs (1-2 inches) but also by its occurrence within mudcracked strata that overlie one of the most important eurypterid horizons in New York.
   Not obvious in the photos, mudcracks occur within the slabs.  Westward, stromatolites be- come even more important--the water must have been deeper-- and the stromatolites be- come much larger. Within the underlying Victor Dolostone, particularly in Canada, large thrombolites appear.
   These stromatolitic layers are part of the
Eurypterus remipes Biozone.  The specimens were recovered from an outcrop in the town of Litchfield, New York.  The site has yielded hundreds of specimens of the common Eurypterus remipes and associated fossils.
   The large slabs of stromatolites and asso- ciated mudcracks are currently in the Yale Peabody Museum, New Haven, Connecticut.

Samuel J. Ciurca, Jr., October 11, 2005