Fossil shorelines of the Ulverstone district

Abstract

The Ulverstone district covers part of the coastal lowlands of the North-West Coast district of Tasmania, centred upon the Leven River, some 12 miles west of the southernmost point on the Tasmanian shore of Bass Strait. A series of well marked older shorelines is found along and below the coastal escarpment. Included are shorelines at 110, 65, 45, 35, and 3 feet above mean higher high water mark, which, at Ulverstone, is 10 feet above State Datum. The highest shoreline is interpreted as representing a late high sea level of the MindelRiss Interglacial. The 65 foot shoreline, the Ulverstone shoreline (45 feet) and the Glenhaven shoreline (35 feet) are interpreted as being Last Interglacial. The Glenhaven shoreline is associated with cobble material thought to be marine-redistributed glacifluvial material from the Forth river. It may constitute further evidence for two phases of Tasmanian glaciation. The Brigadoon shoreline is thought not to require a rise in sea level to 3 feet to explain its morphology. Its age is interpreted as being Holocene. Benches on the sides of Buttons Creek and Claytons Rivulet are structural in origin. but fragments of valley fill terraces in the Leven valley are thought to be related to older shorelines. Parallels are drawn between landforms of the present coastline and landforms existing on fossil shorelines in the area and between fossil shorelines at Ulverstone and those elsewhere in Tasmania and King Island.