Now it is certainly the case that many fine vineyards are on limestone or chalk - Champagne, Chablis, Jerez, Vouvray - but I think it is far from the case that alkaline soils are necessary. Acidic soils are fine for the appropriate varieties. I believe that academic studies have shown that what matters most for good viticulture for wine is the drainage structure of the soil, not its chemical composition.

When I was visiting the Torres vineyard in Chile, or at least their visitor centre which at one of their old vineyards right on the main Panamericana road, as the oldest commercial plantings often are, they told us about their new special vineyard where they hoped to make their finest wines. They had searched very carefully for just the right place, and ended up choosing somewhere with a slate geology. Now slate usually occurs in places I think of as acidic. So here is one of the world's finest viticulturists deliberately choosing a slate soil. My understanding of many of the finest vineyards on steep river banks in Germany are on acidic soils. Alsace is on granite. There are also famous vineyards in many places on sandy soils, and sand is acidic.