The Aymestry limestone and shales date from circa 420 million years ago and are some of the oldest limestones on the planet. It is scattered with brachiopod and occasional orthocone fossils. Pudford Hill was elevated and fractured during the rise of the East Malvern fault over 300 million years ago. Weathering and erosion has washed away superficial lime, but deeper down and at the lower spring sites, rich alkaline lime deposits can be found. Clays form as part of the weathering process and increase in their proportion to limestone from 1/3 above to 2/3 just below the vineyard. The limestone is particularly rich in magnesium, which is an essential element for healthy vines. The magnesium is as high as 1:2 compared to calcium, which is thought to be due to the more stable chemical formula of magnesium carbonate over time. This accounts for a slight pink hue in certain light conditions in a similar way to the Dolomites in Italy. Pictured here are Upper Southwood limestone brachiopod fossils from a shallow terroir pit in the Pinot Noir planting zone.