The supposed Perth Readvance in the Perth District

Synopsis In the course of a detailed investigation of the glacial deposits in the Perth district, only at Moneydie, where at a single locality two till layers are separated by stratified sediments, and in the Almond valley, where kettled outwash gravel rests on laminated marine silts and clays, was evidence found which appears to support the concept of the Perth Readvance, proposed by Simpson (1933) and dated between about 13 500 B.P. and 13 000 B.P. by Sissons (1967a). Readvance of ice at Moneydie is, however, believed to be a local event confined to the valley of the Shochie Burn and an explanation for the sedimentary relationships in the Almond valley is suggested which is compatible with the retreat of a major ice-sheet from the Angus coast. The sequence of sea-level changes inferred from the deposits in the lower Almond valley does not support the concept of an important readvance, nor does the general sequence recognized in Central Scotland by Sissons and others (1966). The Main Perth Shoreline, associated by Sissons and Smith (1965) with the supposed Perth Readvance, is believed to reflect abundant sedimentation at a time when rapid eustatic sea-level rise accompanying an abrupt climatic amelioration kept pace with the isostatic response by the land.