Article was published in the February 2017 WCGMC Newsletter
Sometimes it is fun to just explore for fossils or minerals by visiting an unknown location, perhaps one with potentially appropriate geology, but not a site with documented fossils or minerals. One may not find much, but occasionally one stumbles onto something completely unexpected and equally interesting. In the fall of 2015 Stephen Mayer and I had such an experience when we decided to investigate the geology along Reeder Creek in Varick, NY.
Leave it to the field trip leader of the Wayne County Gem and Mineral Club, Bill Chapman, to find something new! Well, not exactly new, but certainly unusual. Plumalina plumaria were first described by Hall (1878). Yes, they look like feathers, and one might want to classify them as ferns or plants of some sort, but the latest understanding of these rather rare fossils is that they were hydroids (Muscente and Allmon, 2013). Hydroids are a class of small predators that are related to jellyfish. Dominated by soft-body parts hydroids are not well preserved in the fossil record causing extinct species to often be labeled Incertae Sedis in many fossil lists. Incertae Sedis are extinct organisms with unknown or uncertain relation to known phyla.
I have written about Green’s Landing east of Canandaigua Lake after each of my summer visits the past 4 years. This time I will keep the words to a minimum and illustrate a wonderful joint trip with mostly pictures.
It happened in a flash. At our April Friday club meeting, trip leader Bill Chapman announced that we had been granted permission to enter Seneca Stone Quarry on the upcoming Monday and wondered who might be free and interested. Seneca Falls is quite close and apparently we either have a lot of idle folk in the club or a lot of anxious collectors ready to get busy. Eleven folks indicated interest and in a slight mist all eleven converged on the quarry site just south of Seneca Falls ready to collect on Monday morning April 11th.
OK. Admit it, you thought this would be a note about the spectacular doubly terminated clear quartz crystals hiding in vugs in dolostones. Referred to as Herkimer diamonds, and known to mineral enthusiasts from across the country simply as “Herks” there has sure been enough written about them to last a lifetime. And goodness knows we all like to travel to Herkimer County to collect them. But no, this is not just another article about quartz.
Stromatolites are bio-chemically supported structures formed in shallow water when microscopic cyanobacterial material (formally known as blue-green algae) acts to bind and eventually cement sedimentary grains into what are essentially microbial mats. Changing climatic conditions, water depth, sediment influx, or the biology of the micro-organisms themselves leads to finely layered biochemical accretionary structures.
There are many well known fossil collecting sites in the creeks and gullies draining into the Finger Lakes (places like Kashong Gully, Deep Run, and Portland Point to name a few). But for every well documented site there are a dozen lesser known locales where drainages into the Finger Lakes expose the fossil rich strata of the 385 million year old Middle Devonian Hamilton Group. Indian Creek, near Williard on the eastern side of Seneca Lake, is one such location.
The New York State Geological Association (NYSGA) held its annual meeting in Plattsburgh in September. The event, hosted by SUNY-Plattsburgh, featured field trips to several Adirondack sites and I attended one on both days of the event. But we will leave that to a subsequent post. This note focuses on an outcrop just outside Plattsburgh where the gastropod Maclurites magnus can be found. Encouraged to visit the site by a SUNY-Plattsburgh geology student, I found time Tuesday September 15th to spend a couple hours walking the outcrop with New York Paleontology Society Field Trip Leader Ray McKinney, who just so happens to live in Plattsburgh. Meeting him on this trip was an unexpected bonus to attending NYSGA.
Having been rained and flooded out in June, the WCGMC found a way to squeeze a trip Alden into its August schedule visiting the ever popular site on Saturday August 29th. This time the weather was perfect, the water was low, and, as always the fossils were there to be collected. The formidable Ledyard shale cliffs in the creek bed have been a favorite site for collectors for several decades, but winter erosion always seems to expose new ones to extract with a little digging.
It was a large, enthusiastic group of all ages from two local clubs that gathered on August 9th to trek into Green’s Landing on a fossil hunt. Stephen Mayer led the Wayne County Gem and Mineral Club contingent while Dan Krisher (also a WCGMC member) led the Rochester Academy of Science Fossil Group. The total group numbered 27 with about an equal number from each organization. It was a wonderful way for folks in each group to meet fellow fossil enthusiasts while doing what they enjoy most, digging in the Middle Devonian. And Green’s Landing was ready for us with as diverse and prolific assemblage of fossils as one could imagine.
Sheds, NY roadcut was the “Site of the Month” in the June 2015 WCGMC News
Many of us have become familiar with exposures of fossil-bearing Middle Devonian Hamilton Group in the creeks and gulches draining into the Finger Lakes. And we may have ventured west to Penn-Dixie or other Buffalo region sites. But there are also numerous sites within these same geologic units in central New York. One small site is a simple roadside exposure on Dugway Road, just 2.4 miles northeast of Sheds, Madison County, NY (GPS N 42º 49.94’, W 75º 47.72’).
Spring has arrived and Wayne County Gem and Mineral Club did not let any grass grow under its feet before activating its field season. In fact, we did not even let the snow melt.
It was April, it was opening day, and there were diamonds involved. But no, it was not baseball. Rather, April 1 is opening day for “Herkimer diamond” hunting at Ace of Diamonds Mine in Middleville, NY and 12 intrepid WCGMC members put on their boots and their woolies and made the annual trip. Exposure was limited and the snow prevented the owners from bringing in new rock. But there were still “diamonds” to be found and the sun was out to warm our hearts if not our hands. April 1 may actually be more tolerable than August 1. We even signed up a new member while digging, welcoming Donna Dow to our growing family of crazed collectors.
“Site of the Month” article I wrote for Nov. 2014 WCGMC News
More than two decades ago, WCGMC member Stephen Mayer did his M.S. at SUNY-Fredonia focusing on the stratigraphy and fossil assemblages of the Jaycox member of the Ludlowville Formation. A small creek on the east side of Canandaigua Lake provided wonderful exposure of the section and became the key exposure for his work. On Saturday September 27th Stephen returned to his old haunt, this time leading 17 members of our club on a fossil hunt at Green’s Landing. Naturally we learned a little about the local stratigraphy from Stephen also as we hiked about 1200’ up the creek, mostly through Wanakah member shales.
Everyone was clean at this point !
NOTE ADDED OCTOBER 4, 2017: The property in Deep Run has changed ownership and the new owner is NOT allowing collecting or trespassing. The fossil-rich beds described in this note can no longer be visited. WCGMC will not schedule any more trips to Deep Run.
Article I wrote for “Site of the Month”, WCGMC News, Sept. 2014
Devonian Fossils at Deep Run
Most residents of western New York carry on their daily business without any knowledge that they live in a region with some of the richest and most diverse fossil collecting in the United States. Those of us in the WCGMC are lucky to know how blessed with are with our collecting opportunities. But do we know the series of geologic events that led to this unique opportunity?
There are other fossil-bearing stratigraphic units in New York, but here we discuss the prolific Middle Devonian Ludlowville Formation within the Hamilton Group. About 385MY ago an inland shallow sea occupied much of western New York and both the sea and the benthic bottom literally teamed with marine life. Corals (both rugose and tabulate), brachiopods, gastropods, crinoids, and, of course, those highly sought after trilobites thrived communally in the shallow seas behind the continental mass to the west and inboard of the Catskill Delta and Acadian Mountains to the east.
June, 2016 update on Land Ownership:
WCGMC has been informed by the new owner of the property off Route 20 in Alden that the Spring Creek area where we have enjoyed collecting pyritized fossils for a long time is now off limits to collecting. The new owner has informed us that in the future he will treat “fossil collectors as trespassers”. Given the new owner’s wishes, as of June, 2016 WCGMC is not planning any future trips to this area and the site should be considered closed to collecting.
Minerals and Fossils Together
Many of us have a special passion for collecting aesthetic and/or unusual minerals, while others prefer the varied forms and diverse variety offered by the early-mid Paleozoic fossil collecting that can be done in western New York. There is one site that can please both groups of collectors. Along Spring Creek in Alden, NY, the rich and diverse Devonian fossil assemblage we have all come to know and love is locally fully pyritized. Opening the fissile shale surface not only reveals a 380 MY old fossil, but a shiny mineral specimen as well. The prize is a pyritized fossil. Cephalopods, brachiopods, and ammonites are the most common, but two species of trilobites have also been found completely replaced by the iron sulfide mineral pyrite.
Just north of US Route 20 as it passes through the small town of Alden, NY, Spring Creek has carved itself deeply into the Middle Devonian Ledyard Shale Member of the Ludlowville Formation. Known for decades, the site is readily available to all with two legs, a hammer, a backpack (or even large pockets), and the willingness to perhaps get a little wet and mostly certainly muddy. A short hike along well beaten trails leads to the creek which can be accessed at several sites. Fourteen of us can be seen at one of those sites in the cover photo above.
An article I wrote for the April 2014 WCGMC News
The Rochester shale comprises the upper 85’-90’ of the Middle Silurian Clinton Group in upstate New York and southern Ontario. The upper two-thirds of the unit contain numerous grey limestone beds, which can be sufficiently resistant to form outcrops, but which are poor in fossil content. The lower 20’ of the Rochester shale is notoriously susceptible to erosion such that outcrop exposure is rare. Unfortunately, it is this rapidly weathering unit at the base that contains the abundant fossil assemblage (specifically trilobites) for which the formation is famous. The best visible exposure of the full Rochester shale section is in the gorge walls of High Falls on the Genesee River. However, this section is agonizingly unapproachable for fossil collection, particularly so the lower 10-20’ of section best known for fossil diversity and abundance.
Over 200 invertebrate fossil species have been identified from the Rochester shale including corals, brachiopods, bivalves, gastropods, cephalopods and crinoids. But, it is the spectacularly preserved trilobites that have attracted collectors to the Rochester shale since James Hall first detailed their occurrence in the 1840’s. The diverse fauna combined with the fine grained shale beds and thin limestone units indicate that the Rochester shale was deposited in warm, well oxygenated marine waters of intermediate depth. But where does one find outcrop to search for fossils?