Parachucla Formation

The Parachucla Formation was defined in 1908 by Earle Sloan as "weakly lithified shales and mudstones, olive-grey to dark-greenish-grey in color, that crop out on the Savannah River".

No indication of the formation (or Porters Landing Member) was found in bore holes in Evans County, to the west of Richmond Hill, or at Fort Pulaski, to the east.

Shells from the Parachucla Formation exposure at White Springs in northern Florida yielded age estimates of 23.9 to 24.7 Million years ago (Ma).

[9] The Parachucla Formation (Porters Landing Member) in northern Florida is associated with the White Springs Local Fauna, consisting of fossils of 57 vertebrate species from the Arikareean stage of the late Oligocene epoch.

The fossils of the White Springs Local Fauna have been collected from sites on an approximately 10 km long stretch along the Suwannee River where the Parachucla Formation is exposed.

Other small land mammals in the White Springs Local Fauna include a lagomorph (Palaeolagus or Megalagus), two bats, and a marsupial.

[11][12] Most of the land vertebrate fossils in the White Spring Local Fauna are teeth or post-cranial bones of smaller animals.

[14] Sixty-five taxa of invertebrates have been identified in the Porters Landing Member of the Parachucla Formation at the White Springs exposure in north Florida.

Included in these are the bivalves Chlamys acanikos and Ostrea normalis and the barnacles Concavus crassostrictola, Balanus reflexus and a species of Solidobalanus.