Geologic units in Tioga county, New York

Upper Walton Formation (Upper Devonian) at surface, covers 50 % of this area

Shale, sandstone, conglomerate.

Gardeau Formation (Upper Devonian) at surface, covers 31 % of this area

Shale, siltstone; Roricks Glen Shale.

Sonyea Group (Upper Devonian) at surface, covers 13 % 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.

Beers Hill, Dunn Hill, Millport, and Moreland Shales; Grimes Siltstone (Upper Devonian) at surface, covers 3 % of this area

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

Nunda Formation, West Hill Formation (Upper Devonian) at surface, covers 2 % of this area

Nunda: sandstone, shale; West Hill: shale, siltstone; Corning Shale.

New Milford Formation (Upper Devonian) at surface, covers < 0.1 % of this area

Sandstone, shale.

Genesee Group (Upper Devonian) at surface, covers < 0.1 % 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.