The Chablis appellation is located in the northernmost part of the Burgundy region. The only grape that is permitted in Chablis, is Chardonnay. The cool climate in Chablis is ideal for producing Chardonnay grapes with higher acidity. Acidity, provides the structure and finish in a wine. Chablis sits in a valley, on either side of the River Serein. The best vineyards are located on the slopes of the valley because those vineyards have the most optimal exposure to sunlight.  As a result, grapes that are grown on the slopes of the valley have a higher concentration of fruit aromas and flavours. The highly prized Chablis Premier Cru and the Chablis Grand Cru vineyards are located on the ideal, south-facing hillsides. Whereas, basic village level Chablis or Petit Chablis vineyards are located on the plains or on the north facing hillsides of the valley. In addition, the Chablis Premier Cru and Chablis Grand Cru vineyards are planted on Kimmeridgian soil which is composed of limestone, clay and fossilised oysters shells. This type of soil imparts an appealing mineral or flinty note to the wines.