Geology
Coonawarra's terra rossa soil is one of the most famous terroirs in the New World, covering an area of just 15 km x 2 km north of Penola. It lies on a shallow limestone ridge, raising it above the swampy land either side - it is no coincidence that the Riddoch Highway follows this ridge as carters sought the firmest ground in times past. This special bright red soil is clearly visible on an aerial photo.
To the west of the ridge lies black rendzina soil which is poorly drained, and so is much less favourable for vines. There is also a 'transitional', or brown rendzina, soil which grows vines quite successfully. This geological complexity led to many disputes during an eight year period before Coonawarra was entered on the Register of Protected Names. At least one vineyard (belonging to Penola High School) has the boundary pass through the middle.
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