The shale preserves fossils dating back to the Early Cambrian period (Atdabanian in the local timescale, about 520 to 513 Ma).

[1] The oldest Cambrian series of the area was deposited in the Franklinian Basin and is poorly exposed in fragmentary, heavily metamorphosed outcrops in Peary Land.

The Buen Formation forms part of the southern shelf succession of the Franklinian Basin of North Greenland and the Canadian Arctic Islands.

It thickens to around 700 metres (2,300 ft) in northern Peary Land where it comprises a mud−rich transitional succession into deep water trough deposits of the Polkorridoren Group.

Dark grey to black mudstones form part of this transitional succession from the shelf to the slope.