Geologic units in Ontario county, New York

Skaneateles Formation (Middle Devonian) at surface, covers 12 % of this area

Levanna Shale, Stafford Limestone Members.

Genesee Group (Upper Devonian) at surface, covers 12 % of this area

West River Shale; Genundewa Limestone; Penn Yan and Geneseo Shales; all except Geneseo replaced eastwardly by Ithaca Formation-shale, siltstone and Sherburne Siltstone.

West Hill and Gardeau Formations (Upper Devonian) at surface, covers 10 % of this area

Shale, siltstone; Roricks Glen Shale; upper Beers Hill Shale; Grimes Siltstone.

Akron Dolostone (Upper Silurian) at surface, covers 10 % of this area

Bertie Formation - dolostone, shale.

Camillus and Syracuse Formations (Upper Silurian) at surface, covers 8 % of this area

Shale, dolostone, gypsum, salt.

Onondaga Limestone (Middle Devonian) at surface, covers 8 % of this area

Seneca, Morehouse (cherty), and Nedrow Limestone Members, Edgecliff cherty Limestone Member, local bioherms.

Ludlowville Formation (Middle Devonian) at surface, covers 7 % of this area

In west: Deep Run Shale, Tichenor Limestone, Wanakah and Ledyard Shales, Centerfield Limestone Members. In east: King Ferry Shale and other members, Stone Mill Sandstone Member.

Sonyea Group (Upper Devonian) at surface, covers 6 % of this area

In west: Cashaqua and Middlesex Shales. In east: Rye Point Shale; Rock Stream ("Enfield") Siltstone; Pulteney, Sawmill Creek, Johns Creek, and Montour Shales.

Ludlowville Formation (Middle Devonian) at surface, covers 6 % of this area

Deep Run Shale, Tichenor Limestone, Wanakah and Ledyard Shales, Centerfield Limestone Members.

Beers Hill, Dunn Hill, Millport, and Moreland Shales; Grimes Siltstone (Upper Devonian) at surface, covers 5 % of this area

Beers Hill, Dunn Hill, Millport, and Moreland Shales; Grimes Siltstone.

Moscow Formation (Middle Devonian) at surface, covers 4 % of this area

In west: Windom and Kashong Shales, Menteth Limestone Members; In east: Cooperstown Shale Member, Portland Point Limestone Member.

Moscow Formation (Middle Devonian) at surface, covers 4 % of this area

Windom and Kashong Shales, Menteth Limestone Members.

Marcellus Formation (Middle Devonian) at surface, covers 2 % of this area

In west: Oatka Creek Shale Member; In east: Cardiff and Chittenango Shale Members, Cherry Vale Limestone and Union Springs Shale Members.

Lower Beers Hill Shale (Upper Devonian) at surface, covers 2 % of this area

Dunn Hill, Millport, and Moreland Shales.

West Hill and Gardeau Formations (Upper Devonian) at surface, covers 1 % of this area

Shale, siltstone; Roricks Glen Shale; upper Beers Hill Shale; Grimes Siltstone.

Nunda Formation (Upper Devonian) at surface, covers 1 % of this area

Sandstone, shale.

Tully Limestone (Middle Devonian) at surface, covers 1 % of this area

Tully Limestone

Wiscoy Formation (Upper Devonian) at surface, covers 0.4 % of this area

Sandstone, shale; Hanover and Pipe Creek Shales.

Vernon Formation (Upper Silurian) at surface, covers < 0.1 % of this area

Dhale, dolostone.

Lower Beers Hill Shale (Upper Devonian) at surface, covers < 0.1 % of this area

Dunn Hill, Millport, and Moreland Shales.

Camillus, Syracuse, and Vernon Formations (Upper Silurian) at surface, covers < 0.1 % of this area

Shale, dolostone, salt, and gypsum.

Marcellus Formation (Middle Devonian) at surface, covers < 0.1 % of this area

Oatka Creek Shale Member.