18 March 2012
The weather has been freakishly nice for March in Buffalo, so yesterday I decided to chuck any ideas of getting work done and went fossiling with a friend instead. The area where I live sits right on top of the Devonian Onondaga limestone, so I’m already surrounded by a very fossiliferous unit (it’s full of things like coral and brachiopods and crinoids). But for a special locale, it’s worth it to head down to Eighteen Mile Creek, which flows into Lake Erie about 12 miles southwest of Buffalo.
The scenery is lovely here – to get to the fossil site, you take a short hike through woods that border the creek and the marshy areas at the lake outlet. But the best part is at the end of the walk: Trilobites!
Eighteen Mile Creek is one of the best places in Western NY to find trilobites (and other fossils as well). It exposes the Wanakah Shale, another Devonian unit. Here’s what UB’s Geology Department website has to say about it:
“At its type locality north of Eighteen Mile Creek along Lake Erie shore, the Wanakah Shale consists of about 19.8 m of medium gray, soft, fossiliferous shale and shaly mudstone with several calcareous bands and zones of larger concretions. The highest beds of the Wanakah Shale exposed just below the Tichenor Limestone contain a high diversity fossil assemblage termed the Demissa and Stictopora beds of Grabau (1898, 1899). These units yield over 80 species of macrofossils and are particularly rich in brachiopods and bryozoans.
“At Eighteen Mile Creek, the Tichenor Limestone is a resistant, 30-40 cm thick ledge-forming crinoidal biospharite and biomicrite. It contains numerous large rugose corals (Heliophyllum, Eridophyllum) and heads of the tabulate coral Favosites hamiltoniae, large crinoid columns, fenestellid bryozoans and brachiopods. The large bivalves Plethomytilus, Actinopteria, and Goniopora, are locally abundant in the upper surface of the Tichenor Limestone.”
To give you a better idea of the stratigraphy, here’s a diagram of local Devonian units:
Walking along the beach is one easy way to find fossils, but you can also bring along a rock hammer and split chunks of the shale apart (this tends to be where the trilobites show up). We did both, and here are some of our finds:
For more information on Western NY Geology (and fossiling at Eighteen Mile Creek and other locales), check out these links:
- Geology of Western NY Guidebook (a bit old, but worth a read!)
- Devonian Stratigraphy and Fossil Assemblages of Western NY
- Fossilguy.com’s page on Eighteen Mile Creek collecting