perislands

Perislands are a proposed class of coastal landforms consisting of a circular or oval raised rim encircling a lower central basin. The term combines periglacial geomorphology with island form and is used to describe a pattern of shoreline landforms that arises from distinct sediment and ice-related processes.

Formation is attributed to the interaction of frost action, solifluction, and differential sediment transport along cold, wave-active coasts. Frost heave and ice-wedge processes push coasts upward at the rim, while interior zones are eroded or ponded, creating a central depression that may persist seasonally as a wetland.

Morphology commonly includes a distinct rim that stands a few decimeters to a couple of meters above the adjacent water level, with a narrow interior channel or basin. The overall outline is circular or irregular but retains a ring-like symmetry in plan view.

Perislands are most often discussed in Arctic and sub-Arctic coastal settings, where seasonal freeze-thaw cycles and tidal action combine with soft-sediment shorelines. They can be transient features that change with warming temperatures or sea-level fluctuations.

Ecologically, perislands may host specialized salt-tolerant vegetation, wetlands, and invertebrate communities, while their ring morphology can influence local hydrology and sediment trapping. They may also affect navigation in regions where they occur in shallow, busy coasts.

In the geomorphology literature, perislands remain a debated concept, with some researchers treating them as distinct, others considering them a variant of shore platforms or a transient stage in coastline evolution. More field documentation is needed to establish criteria and prevalence.