The dark-skinned Pinot noir and Pinot meunier give the wine its length and backbone. They are predominantly grown in two areas – the Montagne de Reims and the Vallée de la Marne. The Montagne de Reims run east–west to the south of Reims, in northern Champagne. They are notable for north-facing chalky slopes that derive heat from the warm winds rising from the valleys below. The River Marne runs west–east through Champagne, south of the Montagne de Reims. The Vallée de la Marne contains south-facing chalky slopes. Chardonnay gives the wine its acidity and biscuit flavour. Most Chardonnay is grown in a north–south-running strip to the south of Épernay, called the , including the villages of Avize, Oger and . These are east-facing vineyards, with ' similar to the . The various ' account for the differences in grape characteristics and explain the appropriateness of blending juice from different grape varieties and geographical areas within Champagne, to get the desired style for each Champagne house.