The Pekin Formation was deposited in a rift basin along the Atlantic margin of North America during the breakup of the supercontinent Pangaea during the Late Triassic.

The most common rocks in the Pekin Formation are red to brown sandstones, representing a terrestrial fluvial (riverine) and floodplain environment in a hot, humid climate.

It has yielded both abundant plant and animal fossils, including some of the oldest potential dinosaur footprints in the world and the large predatory crocodylomorph Carnufex carolinensis.

On the surface, the Pekin Formation is exposed only as a long, narrow strip along the western edge of the Sanford Sub-basin.

As such, it unconformably overlies the much older eroded and metamorphosed Proterozoic to Cambrian aged metasediments and metavolcanic rocks of the Piedmont.

The Pekin Formation was deposited in a half-graben that formed as part of a series of rift basins that make up the Newark Supergroup during the breakup of the supercontinent Pangaea and subsequent opening of the Atlantic Ocean.

[1][2] As originally defined by Marius R. Campbell and Kent W. Kimball in 1923, the Pekin Formation spanned the entirety of the lower Deep River Basin, encompassing the lowest sedimentary units of the neighbouring Durham and the Wadesboro sub-basins.

[4] The base of the formation is composed of a roughly 10 metres (33 ft) thick layer of grey conglomerate, historically referred to as "millstone grit".

This unit has been interpreted as alluvial fan deposits made up of material derived from the Piedmont to the west flowing down in a southeasterly direction.

[3][5] Clays from the Pekin Formation have been used extensively for the production of pottery, bricks and tiles, namely the Boren and Pomona pits.

[7][8] The age of the Pekin Formation has been estimated based on biostratigraphy and magnetostratigraphy to the Late Carnian (or Tuvalian), supported by correlations with faunas in western North America.

The Boren pits preserves abundant plant megafossils, most commonly cycads and bennettitales, as well as horsetails, various ferns and conifers.

Some of the most notable finds include an intact specimen of the early palm-like cycad Leptocycas gracilis, as well as a new species of the bennettitale Williamsonia, W. carolinensis, that preserves rare reproductive organs and suggests that it and the leaf Eoginkgoites belong to the same plant.

[2][9] Only vertebrate fossils are known from the upper Pekin NCPALEO 1902 locality, and include a variety of archosaurs and synapsids typical of Late Triassic North America.

[8][9] The online collections of the North Carolina Museum of Natural Sciences list tooth fragments of "Archosaurus" sp.

carolinensis Rostrum fragment Originally misidentified as the sacrum of a large fossil bird and named "Palaeonornis struthionoides".

Originally identified only on the assumption that Placerias was the only dicynodont from Late Triassic North America, later examination confirmed this assignment.