A dome is a feature in structural geology where a circular part of the Earth's surface has been pushed upward, tilting the pre-existing layers of earth away from the center. In technical terms, it consists of symmetrical anticlines that intersect each other at their respective apices. Intact, domes are distinct, rounded, spherical-to-ellipsoidal-shaped protrusions on the Earth's surface. A slice parallel to Earth's surface of a dome features concentric rings of strata. If the top of a dome has been eroded flat, the resulting structure in plan view appears as a bullseye, with the youngest rock layers at the outside, and each ring growing progressively older moving inwards. These strata would have been horizontal at the time of deposition, then later deformed by the uplift associated with dome formation.
The Richat Structure in the Sahara Desert of Mauritania. Once considered to be an impact structure, it is now classified as a geologic dome uplifted by an underlying igneous intrusion.
Structural dome on Baffin Island, seen in a planation surface.
Oblique aerial photo of Upheaval Dome, Utah. Now considered to be a deeply-eroded impact crater, it was for many years believed to be a salt dome.
Caprock of a salt diapir at Cape Breton, Nova Scotia. The white rocks at left center are the gypsum and anhydrite carapace of the diapir.
In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the location where the curvature is greatest, and the limbs are the sides of the fold that dip away from the hinge. Anticlines can be recognized and differentiated from antiforms by a sequence of rock layers that become progressively older toward the center of the fold. Therefore, if age relationships between various rock strata are unknown, the term antiform should be used.
Anticline exposed in road cut (small syncline visible at far right). Note the man standing in front of the formation, for scale. New Jersey, U.S.
Anticline near Ehden, Lebanon
Castlemaine Anticlinal Fold
Harpea's Cave in southern France