The Stony Foundation: A Wine Lover’s Guide to the Secrets Beneath Martinborough’s Vineyards

To the traveller arriving in Martinborough for a weekend of tastings, the landscape around the village square looks remarkably simple. It is flat, unpretentious, and easy to navigate. Unlike the dramatic mountain backdrops of Central Otago or the rolling green hills of North Canterbury, our pocket of the Classic New Zealand Wine Trail doesn't boast about its geography.

But as any wine enthusiast quickly learns, the true magic of Martinborough is hidden right beneath our feet.

Beneath the turf lies a fascinating subterranean world of ancient riverbeds, hidden clay pockets, and limestone scree. When you taste a local Pinot Noir and notice its distinct aromas and structures, you are tasting a direct footprint of the earth. The incredible variety of wine styles found across our four local sub-regions—the Main Terrace, Te Muna Road, Lake Ferry Road, and Dry River Road—is dictated entirely by how nature arranged the soils thousands of years ago.

This article follows on from my earlier piece Understanding Martinborough Pinot Noir. If you haven’t read that one yet, you may find it helpful to start there for context.

The Story of Two Rivers

To understand why Martinborough’s soils are so special, we have to look back at the forces that shaped the region. Thousands of years ago, during the intense ice ages, massive glaciers ground down the nearby Tararua and Remutaka mountain ranges, creating vast amounts of raw sandstone, rock and gravel.

As the ice melted, powerful rivers carried this rocky debris down into our wide valley basin. Two primary water systems did the heavy lifting here: the ancient ancestral pathways of the Ruamahanga River and its swift tributary, the Huangarua River. Over thousands of years, these braided rivers constantly shifted across the landscape, dropping layers of stones, gravels, and silt.

I often begin my tours at Martinborough Village Café & Bar, where this detailed 3D geomorphology map shows how the Ruamahanga and Huangarua rivers shaped Martinborough’s terraces.

Eventually, the rivers carved deeper paths into the valley floor, leaving behind elevated, step-like plateaus. These raised landforms are the famous river terraces where our oldest vines sit today, completely insulated from the modern, damp, and overly fertile floodplains below.

The Main Terrace: Old Stones and Hidden Sponges

The historic heart of the Martinborough wine region is the Main Terrace, right on the fringes of the village. Because this plateau has been raised safely above the modern river levels for thousands of years, it has developed a highly stabilized, legendary soil structure.

If you scrape back the grass in an old vineyard here, you will instantly notice that the topsoil is incredibly thin. In fact, across many of our finest blocks, the fine, wind-blown silt loam—known as loess—can be as shallow as two centimetres deep. Rather than sitting on top of the rocks like a clean, separate blanket, this fine silt has actually sifted downward over millennia, filtering directly into the open gaps and structural cracks between the upper river stones. This means you encounter dense, tightly packed greywacke gravels almost immediately just under the surface, held together by a gritty silt matrix.

Scenes illustrating the thin gravel soils with larger greywacke stones near the surface like this one of a Te Kairanga vineyard on Puruatanga Road are common on the Terrace.

Directly below that stony surface lies the true engine of Martinborough: a deep, massive bed of tightly packed, old greywacke river stones and coarse sand. This stone matrix creates an exceptional drainage system. When heavy autumn rains fall right during the critical harvest week, the water doesn't pool around the grapevines. Instead, it pours through the stone spaces almost instantly, protecting the grapes from bloating or splitting.

Because these stony soils drain so fast and contain very few nutrients, they stop the grapevines from becoming "lazy." Instead of growing lush green leaves, the vines are forced to focus all their energy on producing small, highly concentrated clusters of tiny, thick-skinned grapes. This naturally low yield is exactly what allows our winemakers to produce serious, complex Pinot Noir.

However, there is a beautiful, hidden secret inside these deep gravel beds. They are not just uniform rows of dry rock; they are threaded with thin, horizontal seams of dense clay and fine sand. These hidden clay lenses were created during brief moments in ancient history when the prehistoric rivers slowed down, allowing fine mud to settle before the current picked up again.

The two photos of the same vineyard row in Nga Waka Home Block just a few metres apart illustrate the variability common on the terrace with the dense gravel closer to the surface in the second photo

In a dry summer, these clay seams are a total lifesaver. While the surrounding gravel dries out completely, these thin clay bands act like subterranean sponges, trapping tiny reserves of water deep underground. The roots of our old vines, which dive up to five or six metres deep through the stones, tap directly into these damp clay bands. This minute access to water keeps the vines healthy during a drought, allowing the fruit to achieve steady ripening of the skins and seeds.

Crucially, these clay seams are entirely unpredictable, creating fascinating variations at every level of the landscape:

• Variation Within a Single Block: Soil profiles can shift dramatically within the space of just a few vineyard rows. An ancient, meandering river channel may have left a distinct clay seam running diagonally through one corner of a single block, while leaving the rest of the block as barren, unmixed gravel. The vines sitting directly above that hidden clay line will have access to completely different moisture levels during a hot summer, subtly altering their growth, fruit size, and flavour profile compared to their immediate neighbours.
• Variation Between Vineyards: Across the Terrace, no two properties share the exact same soil recipe. Due to the chaotic way the rivers deposited their sediments over millennia, certain vineyards sit on sites that happen to contain proportionally more clay seams throughout their gravel profiles. These clay-rich sites retain slightly more moisture and nutrients, yielding a plusher, rounder style of Pinot Noir, whereas vineyards sitting on pure, raw gravel beds produce wines that lean heavily into classic, tightly wound, mineral-driven structure.

This beautiful balance of stone and clay—and the micro-variations it creates across the plateau—is exactly what gives classic Terrace Pinot Noir its famous structural depth, savoury complexity, and firm tannins built for aging. It is the driving reason why our local producers increasingly bottle single-vineyard expressions to showcase how small, hidden shifts in subsoil layers can create distinctly different characters in the glass.

The Lake Ferry Road Corridor: The Heavy, Fertile Clay Blanket

Traveling southwest from the village along the Lake Ferry Road corridor, the landscape drops off the ancient Pleistocene terrace and settles onto a much younger, low-lying alluvial landscape. This structural drop replaces the stone-dominated profiles of the village with a heavy, moisture-retentive, and highly distinct soil architecture. It also exposes the vineyards to the cooler southerly airflow funneling up from Palliser Bay, giving this sub‑region a noticeably fresher growing environment than the more sheltered village sites.

This cutting on Lake Ferry Road shows the thick clay seam

The defining characteristic of the Lake Ferry Road sub-region is a thick, uniform, two-metre-deep blanket of heavy yellow-grey clay loam sitting directly over old, buried riverbed alluvial sub-strata. In this zone, the clay is the entire story, completely altering the hydrological and chemical rules for the grapevine root network:

• The Abundance of Chemical Fertility: From a soil science perspective, clay is a naturally rich storehouse for plant nutrition. Because microscopic clay particles carry a strong negative electrical charge, they act like a powerful magnet deep underground, binding tightly to essential minerals and nutrients. While the town's gravel flats are barren and washed out by rain, this heavy clay corridor retains its mineral wealth. For premium viticulture, this high natural fertility presents a paradox: it threatens to fuel excessive vine vigour. If left unmanaged, the roots absorb an abundance of nutrients, forcing the vine to prioritize lush, overgrown green canopy foliage over flavour concentration in the fruit.
• High Water-Retention Capacity: In tandem with its mineral wealth, a two-metre clay profile holds an immense volume of water. During our traditionally dry summers, this acts as an incredible natural buffer, slowly feeding moisture to the vines so they rarely require heavy irrigation. However, in an unseasonably wet summer, this dense clay loam risks holding too much water, requiring aggressive canopy management from the grower—such as intensive under-vine weeding and leaf plucking—to keep the vine's growth balanced.
• Thermal Mass Realities: Unlike the dark river stones of the main village that absorb solar radiation and warm up fast, dense clay acts as a cold thermal mass. It retains significant moisture, meaning the soil takes a long time to heat up in the spring. This naturally insulates the vine roots, delaying budburst and effectively shifting the entire seasonal ripening timeline later into the autumn months compared to the village vineyards. Combined with the cooling influence of Palliser Bay’s southerly winds, Lake Ferry Road consistently experiences a slower, more drawn‑out ripening curve.

This specific soil architecture prevents the development of opulent, heavy fruit profiles. Instead, the fertile, cool, heavy clay soils of Lake Ferry Road produce a highly distinct and compelling style of Martinborough Pinot Noir: linear, vertical, and incredibly vibrant wines driven by refreshing acidity, mineral tension, lacy tannins and a marked florality.

Te Muna Road: The Upper Terrace Masterclass and the Stony Lower Shelf

Located just a short drive east of the township, Te Muna Road offers a spectacular lesson in how nature can create completely different soil environments within a tiny distance. The name "Te Muna" translates from Māori as "The Secret", and its geological secret lies in an elevated, dramatic plateau carved out by the historical movements of the Huangarua River.

When looking at this sub-region, the focus belongs firmly and overwhelmingly on the Upper Terrace. This massive, elevated landform is the true engine room of Te Muna, hosting virtually all of the area’s celebrated vineyards. It represents an older, higher alluvial surface that has been exposed to weathering and wind-blown loess accumulation for tens of thousands of years longer than the main village flats.

An old road cutting on Te Muna Road allows a glimpse of the underlying densely packed stony gravels infused with silt loam and volcanic ash, albeit partly obscured by vegetation

The soil architecture on this upper shelf is highly distinct, consisting of fine silt loams overlaying dense, iron-rich clays and stony gravels that are deeply integrated with ancient volcanic ash. This specific matrix displays highly unique water properties. Because the subsoil contains a significantly higher proportion of weathered, iron-rich clays than the central Martinborough Terrace, the Upper Terrace possesses a modest but highly stable water-holding capacity deep in its profile. It does not suffer from the extreme, aggressive drought flashpoints seen in pure gravel beds. However, because these subsoil clays are dense and tightly packed, the water is held tightly by the soil particles, creating a challenging hydrological environment for the vines.

This structural tightness directly dictates root development on the Upper Terrace. Instead of roots plunging straight down through loose, open stone macro-pores, the vine roots must actively snake and force their way through fractured clay joins and compacted, weathered gravel layers. This resistance naturally restricts vine vigour, preventing the plant from over-producing canopy foliage. The roots develop a highly lateral, fibrous architecture within the mid-soil layers to maximise nutrient uptake from the mineral-rich volcanic ash and clay matrices. This restricted root environment forces the grapevines to produce incredibly low yields of tiny, thick-skinned berries with a massive skin-to-juice ratio.

Because these soils are naturally nutrient-poor and prone to structural compaction, local growers on the Upper Terrace have pioneered highly documented, sophisticated soil improvement practices to maintain vine balance without increasing vigour. To preserve the fragile topsoil structure, winemakers avoid aggressive tillage. Instead, they plant complex, multi-species organic cover crops—such as deep-rooting chicory, daikon radish, clover, and oats—between the rows. The taproots of these crops naturally fracture the dense subsoil clays, creating biological pathways that aid future vine root exploration and oxygen penetration. Furthermore, extensive under-vine composting and the application of organic mulches are widely used across Te Muna to steadily build up microbial life and humus levels. This targeted soil management allows the iron-rich subsoils to release their distinct mineral profile smoothly to the vines, yielding a brooding, deeply complex style of Pinot Noir that leads with dark cherry, forest floor, and wild herbs, wrapped in firm, silky tannins built for long-term ageing.

In stark contrast, the Lower Terrace of Te Muna is a minor, almost non-existent player in the region’s wine narrative. Dropping down closer to the modern bed of the Huangarua River, this younger soil profile is an aggressive, raw, and unweathered matrix of exposed greywacke stones and coarse gravels flecked with limestone washed down from the coastal hills.

A view over the Craggy Range vineyards and extensive irrigation pond on the Lower Terrace from the Upper Terrace escarpment

Because it sits in a low-lying basin, this terrace is an absolute magnet for devastating spring frosts, making traditional viticulture incredibly high-risk. As a result, the land remains almost entirely dominated by seasonal cropping and pastoral farming. The distinct exception here is Craggy Range, who stand as a solitary outlier on this lower shelf. By utilising massive frost protection systems, specialised water storage, and high-density clonal plantings, they have managed to tame this difficult terrain. The Pinot Noir from these rare, lower-terrace pockets retains the dark fruit profile of the region but strips away the complex, clay-driven savoury characters of the upper shelf, replacing them with a dark spice and a sharp, flinty mineral tension.

 Dry River Road: The Warm Hillside Limestone Scree

To find the ultimate contrast to the firm, savoury styles of the village terrace, you simply have to explore the southern edges of the district along Dry River Road. This is the warmest, most sheltered sub-region in the entire district.

The soil structure along Dry River Road is fundamentally different because the vineyards step off the flat river terraces entirely and climb onto gentle, north-facing colluvial hillsides. The soil profile here consists of deep, dark, silty clay loams that are heavily infused with shattered marine limestone and rocky scree that has sloughed down from the high ridges over millions of years.

This cutting illustrates the different soil makeup of the colluvial hillsides on Dry River Road.

Chemically, this limestone introduces an abundance of calcium carbonate into the earth, which completely transforms the growing environment. This active calcium performs a brilliant double-act: it naturally balances the soil pH to unlock vital trace nutrients, and it chemically forces the heavy clay particles to clump together into a loose, crumbly texture. This unique soil chemistry allows the roots to breathe and dive deep without getting waterlogged, while the high calcium levels help the vines grow robust, thick-skinned berries packed with deep flavour compounds.

This hillside layout gives the vines two massive advantages:

• Natural Gravitational Drainage: Because the vines sit on a slope and the limestone keeps the clay structure crumbly, excess rainwater runs off naturally using gravity, preventing the roots from getting waterlogged despite the higher clay content of the soil.
• Thermal Retention: The dark soil and light-colored limestone pieces warm up incredibly fast in the morning sun. The stones absorb that heat all day and reflect it back up into the hanging grapes, accelerating their ripening.

The presence of ancient marine limestone completely alters the chemistry of the earth, helping the fruit achieve a level of rich, plush ripeness that is impossible on the cooler, flat terraces. Pinot Noirs harvested from Dry River Road are consistently generous, round, and dark-fruited, bursting with rich blueberry, dark plum, and sweet spice notes. The tannins here are soft, dusty, and immediately approachable, showing how just a small shift in hillside limestone chemistry can create an entirely different style of wine across the same district.

From the Earth to Your Glass

For a passionate wine lover, tasting a flight of local Pinot Noirs inside a modern tasting room only tells half the story. The true joy of exploring a premium region comes from connecting the flavours in your glass straight back to the hidden physical structures of the earth that grew them.

However, we must also look at the complete picture. Despite the fashionable claims of most modern winemakers about "low intervention" or simply "letting the vineyard speak," the human hand remains a powerful force in shaping the final product. The soil provides the raw canvas, but both clone planting decisions and meticulous winemaking techniques still exert a massive, undeniable influence on the wine in the glass. The magic happens at the intersection of nature and human craft—deciding whether to plant the structured Abel clone or the aromatic Dijon clones to match a specific soil profile, or choosing how much whole-bunch fermentation to use to complement the natural tannins of the site.

When I host a private, educator-led tour, we don’t just drive between cellar doors or get lost in marketing slogans; we unpack this exact interplay between soil, vine genetics, and craft. By standing directly in the vineyards and comparing a structured, age-worthy Terrace Pinot Noir against a bright, mineral style from Lake Ferry Road or an opulent, limestone-sited wine from Dry River Road, you can clearly taste the hand of nature alongside the deliberate choices of the winemaker. It turns a simple day out into a meaningful, personalised journey through New Zealand wine culture.