around 375 Mya, which coincides with timing of the Acadian orogeny that formed the Appalachian Mountains. Though Duke stone contains no fossils, other areas of the Carolina Terrane contain fossilized corals and trilobites that were used to establish that this formation is exotic to the main North American (Laurentia) landmass.
The Duke stone quarry now occupies a five-acre (2.0 ha) section of the Hillsboro Division of the Duke Forest. In new construction and repairs on Duke campus, the use of Duke stone is strictly regulated: "All stones shall be laid on their natural beds, with 20 percent of stone being split face and 80 percent seam face, mixed proportionately to show variations of stone coloring". In recent years, high cost of quarrying the stone, and the irregular knapped ashlar shapes with its associated high stonemasonry costs has led to the university establishing a mix of bricks to imitate the Duke stone colors.
=== Recent construction ===
A number of construction projects in recent years include renovations …
