[2] Current nomenclature usage by U.S. Geological Survey restricts the name Old Port Formation to Pennsylvania, but correlative units are present in adjacent states.

[7] A separate formation, the Oriskany Sandstone, is a lateral equivalent of the Ridgeley Member, but bounded above and below by unconformities.

[5] It is named after Shriver Ridge (the type locality), Allegany County, Maryland, and was originally mapped as the basal unit of the Oriskany Formation.

[6] The Mandata Shale of the Helderberg Group was first introduced by F. M. Swartz in 1938,[10] mainly with reference to the overlying Licking Creek Limestone.

[12] The type locality is a railroad cut 0.3 mi southeast of Corriganville, Alleghany County, Maryland.

[15] The unit consists of layers and nodules of black chert interbedded with light-gray crystalline limestone.

The type locality is a bluff on the south side of Licking Creek, about one mile east of Warren Point, Franklin County, Pennsylvania.