Monocline

block diagram of a monocline

The Grandview-Phantom Monocline in the Grand Canyon, Arizona

Monocline at Colorado National Monument

Monocline formed at tip of small thrust fault, Brims Ness, Caithness, Scotland

A monocline (or, rarely, a monoform) is a step-like fold in rock strata consisting of a zone of steeper dip within an otherwise horizontal or gently dipping sequence.

Formation

Possible modes of formation of monoclines

Monoclines may be formed in several different ways (see diagram)

• By differential compaction over an underlying structure, particularly a large fault at the edge of a basin due to the greater compactibility of the basin fill, the amplitude of the fold will die out gradually upwards.
• By mild reactivation of an earlier extensional fault during a phase of inversion causing folding in the overlying sequence.
• As a form of fault propagation fold during upward propagation of an extensional fault in basement into an overlying cover sequence.
• As a form of fault propagation fold during upward propagation of a reverse fault in basement into an overlying cover sequence.

Examples

• Waterpocket Fold in Capitol Reef National Park, Utah
• Comb Ridge in southern Utah
• Grandview-Phantom Monocline in Grand Canyon, Arizona
• Grand Hogback in Colorado
• Lebombo Mountains in Southern Africa
• Lapstone Monocline in the Blue Mountains (Australia)
• Beaumaris Monocline in Victoria (Australia)
• Purbeck Monocline on the Isle of Purbeck, Dorset, England
• Fore-Sudetic Monocline, Poland
• Sindh Monocline, Pakistan
• Torres Flexure, southern Brazil

See also

• Anticline
• Homocline
• Syncline