GEOGRAPHY, SOILS AND CLIMATE, OF POLISH HILL RIVER

The "Clare Valley", whilst being a catchy marketing term, is in fact, incorrect. There is no single valley. There is a plateau corrugated by ridges that generally run in a north-south direction. The central feature of this plateau is Mount Horrocks (600 m). South of Mount Horrocks there are three valleys: the Wakefield River, Eyre Creek, and the Skillogalee Creek, that join and flow west to Port Wakefield.

Flowing north are the valleys of the Hill River and the Hutt River, that ultimately flow into the Broughton and meet the sea at Port Davis (between Port Broughton and Port Pirie). Polish Hill River is located on the upper reaches of the Hill River.

The soil at Polish Hill River is an acidic red-brown clayey-loam. In contrast to the Watervale sub-region to the south of Mount Horrocks, there is no limestone at Polish Hill River. Geologically the region is of ancient shale and an extension of the famous Mintaro slate. (The slate quarry at nearby Mintaro remains the only site in Australia where it is possible to obtain a sheet of slate large enough for a full-size billiard table). Around the turn of the century drill holes were made at Polish Hill River in the hope of finding coal. The venture failed, and as modern geologists explain, the reason was that the shale of this area was laid down well before the evolution of plant forms. The top-soil is shallow, and the sub-soil is a heavy red clay. The superficial shale is fissured, and decomposing. The fissures extend deep into hard blue shale. It is these deep fissures that the vine roots seek to go deep for water.

Polish Hill River is one of the higher parts of the "Clare Valley", and most vineyards are above 400 m elevation. Rainfall (about 700 mm) is generally regarded to be higher than the three surrounding official weather stations at Clare, Watervale, and Mintaro. Grapes from Polish Hill River ripen two to three weeks later than grapes from Watervale and Clare. The north-south running ridges provide a shading that relieves the vines of Polish Hill River from the last 20 or 30 minutes of the harsh midsummer afternoon sun.

For more information on the matter of soils, we recommend the publication, Soils of the Clare Valley South Australia published by the Department of Water, Land and Biodiversity Conservation, September 2004, Report DWLBC 2004/32 ISBN 0-9752098-9-2