Dynamic beach response to changing storminess of Unst, Shetland: implications for landing places exploited by Norse communities

We present major new findings on the stability of Norse landing places on the island of Unst, Shetland, using a combination of geomorphology, OSL dating, fetch analysis, and sediment transport modeling. Islanders needed reliable access to the sea, and exploited sandy beaches as safe landing places. The persistence of beaches was important for long-term continuity of settlement and could be threatened by stormy conditions. Sediment modeling undertaken on two embayments on Unst, Lunda Wick, and Sandwick, reveals major differences in the ability of sandy beaches to reform in these embayments after the onset of persistent stormy conditions; sandy beaches can endure under these conditions at Sandwick, but not at Lunda Wick. OSL dating of blown sands at Lunda Wick reveals a history of sand blow events pointing to large-scale depletion of beach material throughout the Little Ice Age (beginning circa 1250 CE). This correlates with known sand blows at Sandwick, but here the beach could be replenished from the nearshore environment, something that was more problematic at Lunda Wick. These findings agree with the emerging picture of increased environment pressure from blown sands on communities throughout the North Atlantic, and identifies different models of related beach persistence and change.