Shore platform abrasion in a para-periglacial environment, Galicia, northwestern Spain

The Schmidt Rock Test Hammer was used to study the effect of abrasion on shore platforms in Galicia, northwestern Spain. On platforms where tidally-induced weathering (salt, wetting and drying, etc.) is dominant, rock strength is significantly lower than in areas where abrasion is, or has been active in the recent past. This suggests that abrasion removes weathered surface material, exposing the stronger, less weathered rock below. Abrasion downwearing, measured with a transverse micro-erosion meter, ranged between 0.13 and 1.8 mm yr− 1 over the last year. Most active abrasion occurs in the upper part of the intertidal zone, but weathering is slowly destroying formerly abraded surfaces at lower elevations. These abandoned surfaces were abraded by materials supplied by erosion of fluvio-nival and periglacial slope deposits that covered, or partially covered, parts of the Galician coast during the middle and late Weichselian. During the Holocene, rising sea level and erosion of the slope deposits caused the abrasion zone to gradually migrate up to its present position near the high tidal level. The spatial and temporal role of abrasion on this coast is, therefore, closely associated with the exhumation and inheritance of ancient platform surfaces from beneath Weichselian deposits.