The Sonyea Group is a

geologic group Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Eart ...

in the northern part of the

Appalachian Basin The geology of the Appalachians dates back to more than 480 million years ago. A look at rocks exposed in today's Appalachian Mountains reveals elongate belts of folded and thrust faulted marine sedimentary rocks, volcanic rocks and slivers of ...

. It preserves

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

dating back to the

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, w ...

period. In the western part, it is divided into the

Cashaqua Shale The Cashaqua Shale is a geologic formation in New York. It preserves fossils dating back to the Devonian period. The Cashaqua shale underlies the Rhinestreet Shale member of the West Falls Group, and overlies various other members of the Sonyea ...

at the top, and the

Middlesex Shale The Middlesex Formation is a carbon rich black shale geologic formation found in the Appalachian Basin. It represents one of several transgressive events (rising sea levels) during the Late Devonian. Description The Middlesex is a laminated da ...

at the bottom. In the east, various shale formations are included between the Cashaqua and Middlesex members, including Rye Point Shale,

Rock Stream Formation The Rock Stream Formation (or Rock Stream siltstone) is a geologic formation in New York. It preserves fossils dating back to the Devonian period. See also * List of fossiliferous stratigraphic units in New York This article contains a list of ...

Enfield Formation The Enfield Formation is a Formation (stratigraphy), geologic formation in New York (state), New York. It preserves fossils dating back to the Devonian Period (geology), period. See also * List of fossiliferous stratigraphic units in New York R ...

") Siltstone,

Pulteney shale The Pulteney Shale is a geologic formation in New York. It preserves fossils dating back to the Devonian period. See also * List of fossiliferous stratigraphic units in New York This article contains a list of fossil-bearing stratigraphic uni ...

, Sawmill Creek Shale, Johns Creek Shale and Montour Shale.

References

* * Geologic groups of Pennsylvania Devonian geology of New York (state) {{Pennsylvania-geologic-formation-stub