Description

SHINGLE BEACH RIDGES The Stranded Shingle Beach Ridges north along the western coastline of Upper Spencer Gulf have been provisionally entered for inclusion as a State Heritage Place in the South Australian Heritage Register. There are only 2 other places in the world registered with similar Shingle Ridges being in Egypt and Scotland. A geological phenomenon, these stranded shingle beach deposits have been traced over a distance of some 50kms from near the head of Spencer Gulf southwards along its western shore to Stony Point, and provide a distinctive geological feature which is believed to date back to the Pleistocene period. Consisting of moderately sorted, rounded to sub-angular pebbles and cobbles, the deposits form sinuous, flat topped and well preserved ridges 3-5 metres above present mean sea level. Most are usually narrow no more than 10-15 metres wide. In some areas the deposits form cliffs behind the modern beach. The movement of gravel by present day waves in the northern part of Spencer Gulf is restricted compared with that indicated by the ridges. It appears that the combination of a high sea level (3 metres higher than today), strong easterly winds, and high wave energy dissipation along the shore line, were responsible for the deposits.