The wine area Medoc also has pine forests and long sandy beaches. The Médoc's geography is not ideal for wine growing, with its proximity to the Atlantic Ocean resulting in a comparatively mild climate and high rainfall making rot a constant problem.
It is generally believed that the nature of the region's wine derives from the soil; although the terrain is flat, the excellent drainage is a necessity and the increased amount of gravel in the soil allows heat to be retained, encouraging ripening, and extensive root systems.
With the exception of Château Haut-Brion from Graves, all of the red wines in the 1855 Classification of Grand Cru Classé's are from the Médoc. Many of the Médoc wines that are not in this classification are classified under the Cru Bourgeois system.
Almost all of the region's wine consists mainly of the cabernet sauvignon grape, with merlot forming the majority of the remainder. In addition cabernet franc is usually used in small quantities, with petit verdot and malbec occasionally added.
The most famous appellations in Medoc made up of wine-making communes are Margaux, Saint Julien, Pauillac and Saint Estephe.
The soils in Médoc are Garonne gravel, Pyrenees gravel and clayey limestone with extreme variation in character. There are frequent areas of heavy, clay-rich, moisture-retentive soils better suited for cultivation of the Merlot grape than Cabernet Sauvignon, and vineyards are less densely packed than further south, intermingled with other forms of agriculture.
The soil in Margaux is the thinnest in the Médoc, with the highest proportion of gravel. (The generally received opinion being that poor soil makes good wine.) The gravel provides good drainage.
In Saint Julien the vineyards lie on a bed of sedimentary rock. Unlike the surface soil, which is an unbroken expanse of pebbles, the subsoil is surprisingly complex and is the reason why Saint-Julien wines vary so much in character.
Pauillac is somewhat more elevated than the surrounding area, rising to a peak of nearly 30 metres above sea-level in the region of Château Pontet-Canet. The soil is gravelly, as with most of the Haut-Médoc. The forest to the west shelters the vines from the Atlantic winds.
The sol de grave in Saint Estephe (a soil type containing a mixture of gravels, clay and sand), shared by all AOC wines from the Médoc, contains a slightly higher proportion of clay in this particular area.