Terroir

Gravel Soils: Drainage, Heat Retention and Cabernet Sauvignon in the Médoc

Bordeaux.com says Cabernet Sauvignon, a late-ripening variety, thrives above all on the warm, gravelly soils of Bordeaux's Left Bank.

Bordeaux.com says Cabernet Sauvignon thrives above all on the warm, gravelly soils of the Left Bank, especially in the Médoc and Graves. Its Graves page says gravel and pebbles from the Pyrenees were carried by the Garonne River, and that these soils store heat from the sun's rays during the day, release it at night, and are well drained. In Pauillac, the same source says gravel combined with clay and sand ensures exceptional drainage and forces the vines to plunge their roots deep into the subsoil. In Saint-Julien, Bordeaux.com says the large gravel stones act as natural radiators, capturing heat during the day and releasing it at night, allowing Cabernet Sauvignon to ripen slowly but surely. Cabernet Sauvignon is a late-ripening variety, usually harvested 7 to 12 days after Merlot.

What It Is: Composition and Structure

The Graves appellation is named after the gravel and smooth pebbles deposited by the Garonne, and Bordeaux.com says the word comes from the old French 'grava', meaning a gravelly terrain. In Saint-Estèphe, the same source lists small river stones, white quartz, sandstone, flint, volcanic Lydian stones and millstones in soils made primarily from gravel. In Pauillac the vines root into a mixture of gravel, sand and clay, and in the Graves, Bordeaux.com describes stones, gravel, sand, silt and clay lying atop a limestone, iron hardpan and clay subsoil.

Saint-Estèphe stones named by Bordeaux.com: small river stones, white quartz, sandstone, flint, volcanic Lydian stones and millstones
Pauillac: a mixture of gravel, sand and clay carried down the Garonne River into the estuary over millions of years
Graves: stones, gravel, sand, silt and clay atop a limestone, iron hardpan and clay subsoil
Saint-Estèphe: gravel combined with sandy-clay soils in proportions that vary from plot to plot, over a subsoil of marine limestone

Key Facts

Bordeaux.com says Cabernet Sauvignon thrives above all on the warm, gravelly soils of the Left Bank, especially in the Médoc and Graves
Bordeaux.com says Graves soils store heat from the sun's rays during the day and release it at night, and calls Saint-Julien's large gravel stones natural radiators that allow Cabernet Sauvignon to ripen slowly but surely
Gravel and pebbles from the Pyrenees were carried by the Garonne River, according to Bordeaux.com's Graves page
In Pauillac, Bordeaux.com says Garonne gravel combined with clay and sand ensures exceptional drainage and forces the vines to plunge their roots deep into the subsoil
WSET notes that dark, stony soils store and radiate warmth, while soils with a lot of clay are usually cooler because they absorb and retain water
Cabernet Sauvignon is a late-ripening variety, usually harvested 7 to 12 days after Merlot, and covers 22% of Bordeaux's red plantings (Bordeaux.com, accessed 2026)
The Haut-Médoc's vineyard is divided into well-defined rises known locally as 'cos', formed by erosion and by the Garonne and its tributaries digging their riverbeds during the glacial period (Bordeaux.com)

How It Forms: Geological Origin and Distribution

Bordeaux.com's Graves page says gravel and pebbles from the Pyrenees were carried by the Garonne River. On the Médoc, the same source says the Garonne deposited aggregates and sediments which, combined with erosion, formed clay-limestone layers or so-called 'Pyrenean' gravel hillocks in localized areas. In the Haut-Médoc the vineyard is divided into well-defined rises known locally as 'cos'. Bordeaux.com says they were formed by erosion and by the Garonne and its tributaries, the 'esteys' and 'jalles', digging their riverbeds during the glacial period, so the soils combine sandy gravel layers from the Quaternary period with clay-limestone from the Tertiary period. In Margaux, Bordeaux.com says gravel was transported by the Garonne onto a central plateau 6 km long and 2 km wide, and that the Margaux terroir comprises six types of terraces formed during the Quaternary period.

Source: gravel and pebbles from the Pyrenees, carried by the Garonne River (Bordeaux.com, Graves)
Haut-Médoc: sandy gravel layers from the Quaternary period combined with clay-limestone from the Tertiary period
Saint-Julien-Beychevelle: a gravel layer covering a rectangular area 5 km long and 3.5 km wide, with the alluvial layer split into several Garonne gravel rises from the early Quaternary period (Bordeaux.com)
Margaux: gravel on a central plateau 6 km long and 2 km wide, and a terroir of six types of Quaternary terraces, where Bordeaux.com says large-sized Garonne gravel combines with average-sized pebbles in 'the most remarkable combination of gravel soils in the Haut-Médoc', over a limestone or clay-marl Tertiary terrace

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Drainage and Root Development

Bordeaux.com describes the Médoc's gravel hillocks as providing perfectly drained soils, Saint-Estèphe's soils as meager and perfectly well-drained, and Saint-Julien's Garonne gravel rises as ensuring optimal drainage. In Pauillac, the same source says gravel combined with clay and sand ensures exceptional drainage and forces the vines to plunge their roots deep into the subsoil. Clay behaves differently. Bordeaux.com says soils rich in clay retain moisture and lead to muscular, full-bodied wines, whereas limestone and gravel have good drainage and lead to brighter acidity. WSET notes that soils with a lot of clay are usually cooler because they absorb and retain water well.

Pauillac: gravel with clay and sand ensures exceptional drainage and forces roots deep into the subsoil (Bordeaux.com)
Saint-Estèphe: meager and perfectly well-drained soils (Bordeaux.com)
Bordeaux.com: clay-rich soils retain moisture and lead to muscular, full-bodied wines; gravel and limestone drain well and lead to brighter acidity
WSET: soils with a lot of clay are usually cooler because they absorb and retain water well, which can be useful in drier climates

Heat Retention and Ripening

Bordeaux.com says the Graves soils store heat from the sun's rays during the day and release it at night in the vineyards, and it describes Saint-Julien's large gravel stones as natural radiators that capture heat during the day and release it at night, allowing Cabernet Sauvignon to ripen slowly but surely. WSET states the general principle: soil can magnify the effects of the climate, with light-coloured soils reflecting sunlight and dark, stony soils storing and radiating warmth. Bordeaux.com calls Cabernet Sauvignon a late-ripening variety, usually harvested 7 to 12 days after Merlot. On the Haut-Médoc, Bordeaux.com links the gravel soils to the slow, even ripening of Cabernet Sauvignon.

Graves: soils store heat from the sun's rays during the day and release it at night (Bordeaux.com)
Saint-Julien: large gravel stones act as natural radiators, letting Cabernet Sauvignon ripen slowly but surely (Bordeaux.com)
WSET: light-coloured soils reflect sunlight, while dark, stony soils store and radiate warmth
Cabernet Sauvignon ripens late, usually 7 to 12 days after Merlot, and Bordeaux.com says that because it ripens late it tends to produce wines with moderate alcohol levels

Effect on Wine: Cabernet Expression and Structure

Bordeaux.com describes Cabernet Sauvignon in Bordeaux as highly aromatic, with cassis, licorice and mint and, with time, a hint of forest floor, carried by vigorous tannins and an upright structure. Its commune pages tie the gravel to the wines. In Pauillac it credits the Garonne gravel, with clay and sand, for wines of poise and concentration, and sums up the style as powerful and elegant. In the Graves it says the well-drained soils produce evenly ripe grapes and wines of elegance, finesse and balance. In Margaux it says the meager soils give tannins that withstand the test of time.

Cabernet Sauvignon (Bordeaux.com): cassis, licorice and mint on the nose, forest floor with time, vigorous tannins
Pauillac (Bordeaux.com): powerful and elegant; black cherry, licorice, blackcurrant liqueur, rose petal, iris, cedar and incense
Saint-Julien (Bordeaux.com): silky tannins; blueberry, blackcurrant, blackberry and prune, with tobacco, truffle and leather with age
Margaux (Bordeaux.com): delicacy, smooth tannins and fruity notes, with meager soils giving tannins that withstand the test of time

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Where You'll Find It: Médoc Plateau Terroirs

The Haut-Médoc appellation encompasses six communal appellations: Saint-Estèphe, Pauillac, Saint-Julien, Listrac-Médoc, Moulis and Margaux. Pauillac is home to three of the five Premiers Grands Crus Classés of the 1855 classification: Château Lafite Rothschild, Château Latour and Château Mouton Rothschild. Bordeaux.com (accessed 2026) gives Saint-Julien's Cabernet Sauvignon share as over 60% of its vineyards and says there is nowhere else in Bordeaux where the variety is grown in such proportions. Saint-Estèphe, whose gravel sits over marine limestone, plants 50% Cabernet Sauvignon and 40% Merlot (Bordeaux.com, accessed 2026). South of Bordeaux, the Graves is named after the gravel and smooth pebbles the Garonne deposited. On the Right Bank the balance shifts: Bordeaux.com says Merlot is dominant in Saint-Émilion, Pomerol and Fronsac, in part thanks to the limestone plateau of Saint-Émilion, though where there is more gravel, more Cabernet is planted.

Pauillac: 1,220 hectares under vine and 18 Grands Crus Classés in the 1855 classification, including 3 Premiers Crus (Bordeaux.com, accessed 2026)
Saint-Julien: 910 hectares; Cabernet Sauvignon over 60% of the vineyards (Bordeaux.com, accessed 2026)
Margaux: 1,500 hectares; 21 of the 61 great growths of 1855 are in the appellation (Bordeaux.com, accessed 2026)
Saint-Estèphe: 1,200 hectares; Cabernet Sauvignon 50%, Merlot 40%, Cabernet Franc 7%, Petit Verdot 3% (Bordeaux.com, accessed 2026)
Pomerol, for contrast: clay-gravel and sandy gravel soils over a subsoil rich in iron oxide, known locally as 'crasse de fer' (Bordeaux.com)

Sources and last verified

Primary sources: https://www.bordeaux.com/en/designations/medoc/pauillac/, https://www.bordeaux.com/en/designations/medoc/saint-julien/, https://www.bordeaux.com/en/designations/medoc/margaux/, https://www.bordeaux.com/en/designations/medoc/saint-estephe/, https://www.bordeaux.com/en/designations/medoc/haut-medoc/, https://www.bordeaux.com/en/designations/medoc/medoc/, https://www.bordeaux.com/en/designations/graves-sauternes/graves/, https://www.bordeaux.com/en/grape-varieties/cabernet-sauvignon/, https://www.bordeaux.com/en/mag/blog/the-art-of-the-blend/, https://www.bordeaux.com/en/mag/blog/battle-d-aoc-haut-medoc-vs-pessac-leognan/, https://www.bordeaux.com/en/grape-varieties/merlot/, https://www.wsetglobal.com/knowledge-centre/blog/2021/august/24/how-does-geography-affect-a-wine-s-style, https://www.bordeaux.com/en/designations/saint-emilion-pomerol-fronsac/pomerol/. Last verified 2026-09-28

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Flavor Profile

Bordeaux.com describes Cabernet Sauvignon as highly aromatic, with cassis, licorice and mint and, with time, a hint of forest floor, over vigorous tannins and an upright structure. Because it ripens late, the same source says it tends to produce wines with moderate alcohol levels. On gravel, Bordeaux.com describes Pauillac as powerful and elegant, and Saint-Julien as having silky tannins and blueberry, blackcurrant, blackberry and prune fruit, with tobacco, truffle and leather with age.

Food Pairings

Roast rack of lamb with garlic and herbsGrass-fed beef ribeye with a red wine reductionDuck breast with a black truffle sauceAged hard cheese such as Comté or aged CheddarVenison steak with a juniper and red wine jusSlow-braised lamb shoulder with root vegetables and thyme

How to Say It

Médocmay-DOK

Pauillacpoh-YAK

Saint-Juliensan-zhoo-LYAH(N)

Margauxmar-GOH

Saint-Estèphesan-teh-STEF

Haut-Médocoh-may-DOK

Exam Study NotesWSET / CMS

Bordeaux.com says Cabernet Sauvignon thrives above all on the warm, gravelly soils of the Left Bank, especially in the Médoc and Graves; its Graves page says the gravel and pebbles came from the Pyrenees, carried by the Garonne River.
Two mechanisms: gravel drains well (Pauillac's gravel with clay and sand forces roots deep into the subsoil), and Graves soils store the sun's heat by day and release it at night (Bordeaux.com; WSET: dark, stony soils store and radiate warmth).
Cabernet Sauvignon is late ripening, usually harvested 7 to 12 days after Merlot (Bordeaux.com); Bordeaux.com says Saint-Julien's large gravel stones act as natural radiators that let it ripen slowly but surely; clay-rich soils are usually cooler because they absorb and retain water (WSET).
Haut-Médoc soils combine Quaternary sandy gravel with Tertiary clay-limestone; Margaux's terroir comprises six types of Quaternary terraces; Saint-Estèphe's gravel sits over marine limestone.
Commune Cabernet shares (Bordeaux.com, accessed 2026): Saint-Julien over 60%; Saint-Estèphe 50% with Merlot at 40%. On the Right Bank, Merlot dominates Saint-Émilion, Pomerol and Fronsac, in part thanks to Saint-Émilion's limestone plateau.

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