Flark

A flark is a depression or hollow within a bog, typically occurring as one of a series of parallel depressions separated by low ridges called strings, forming the strikingly patterned string bog landscape. Early researchers attributed flarks to frost heaving, but that explanation fails where flarks occur in regions with no frost heaving, and two other mechanisms are now favored. In one, peat that has built up to considerable thickness slides downslope under its own weight, and irregularities in the ground beneath obstruct the movement, tearing the peat and leaving a depression on the downslope side. In the other, some parts of a bog decay faster than their surroundings, and the resulting surface depression becomes a flark. Documented examples include string bogs in Fundy National Park in New Brunswick, Canada, and bogs in Scandinavia, showing that the feature develops across widely separated bog ecosystems.