When discussing Bordeaux, one of the first distinctions one may come across is the differentiation between right and left bank. The Gironde estuary cuts the region in two with Médoc and Graves on the left bank and St-Émilion and Pomerol on the right.
The left bank is distinctive because of its gravel, free draining soil and use of Cabernet Sauvignon as a primary grape blended with Merlot, Malbec, Cabernet Franc, Petite Verdot, and rarely Carmenere. The right bank has more clay like soils focusing on Merlot and Cabernet Franc varieties. Because the climate in Bordeaux is marginal and wet the fact that all these grapes bud and ripen at different times works as a sort of crop insurance. If disaster strikes (like mold, or an untimely rain) one grape may be damaged at flowering or ripening while the others may not be at a vulnerable stage to be adversely affected. This means depending on the weather and vintage the exact blend of grapes will change to reflect the success of the season.
The top wines of the left bank have powerful, fine tannin and deep color from thick skinned Cabernet Sauvignon, plum fruit and muscular tannin from the Merlot and Malbec, fragrant elegance of Cabernet Franc and deep brooding savory black fruit from a small percentage of Petite Verdot in the best years. The gravel soils in this region allow the soil to warm more easily and reflect heat up at the vines allowing Cabernet Sauvignon to grow here. Conversely, the right bank has more clay like soils that are cooler and favor the growth of Merlot and Cabernet Franc. Merlot can give quite powerful structural tannins in the finest wines, but in general has a softer, plush rich red fruit character than the left bank. Again, like on the left bank, Cabernet Franc gives elegance and aromatics. The hue of right bank is usually medium to deep ruby as opposed to the inky purple left bank wines.
