The Medina Group or Cataract Group is a geologic group in

New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...

. It dates to the

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

period Period may refer to: Common uses * Period (punctuation) * Era, a length or span of time *Menstruation, commonly referred to as a "period" Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (o ...

. The group includes the Whirlpool Sandstone,

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

, Devils Hole Sandstone, Grimsby Formation, Thorold Sandstone, Cambria Shale, Cabot Head Shale and Kodak Sandstone.

References

Geologic groups of New York (state) Silurian New York {{NewYork-geologic-formation-stub