Terroir in Napa? Part I – Amazing how things change with the passage of time. For instance, who would have thought Napa winegrowers would become so interested in terroir, the reciprocal notion that soil, geography, climate, and human intervention played such a vital role in the production of unique, world-class wine? But here we are, in the autumn of 2011, with most serious Napa growers speaking of nothing but terroir, and how the sub-appellations of the valley have come to be recognized as a crucial, if not limited, aspect to the development of less generic, better crafted wine.
Now, as a crucial part to understanding how terroir is interpreted in the Napa Valley, an ideal place to start is by looking at the fifteen sub-appellations that comprise the region as a whole. Oftentimes demarcated more as a matter of climatic convenience than outright physical geography, the sub-appellations of Napa serve as a very useful tool in grasping the fundamentals of this surprisingly varied—particularly in terms of soil—winegrowing region.
Let’s start with Carneros AVA, located in the southernmost part of the valley and shared with Sonoma County to the west. This is the coolest sub-appellation in Napa, heavily exposed to the cool winds coming off the San Pablo Bay and thus home to superb examples of Pinot Noir and Chardonnay, as well as some of the finest sparkling wines in California. Indeed, Carneros is often considered the most significant exception to the rule that Napa is incapable of producing world-class Pinot Noir and cool-climate Chardonnay. Shallow clay-loam soils dominate the area—much less fertile than the Napa Valley floor.
Northeast of Carneros, we come to the Oak Knoll District AVA. Established as an official sub-appellation only relatively recently, here lies an additional cool-climate area of incredible potential. At present, Cabernet Sauvignon, Merlot, and Chardonnay have each performed splendidly, though virtually every other major varietal seems happy here. Soil contents vary from volcanic deposits in the northwest to varying traces of gravel-clay loam in the south and east.
West of here is Mount Veeder AVA, a superb sub-appellation located in the Mayacamas mountain range separating Napa and Sonoma. With elevations reaching as high as 650m (important for day-night-time temperature variation), the speciality of Mount Veeder is flavourful, well-structured Cabernet Sauvignon-blends, often capable of significant aging. Soil contents are quite high in acidity and boast heavy volcanic deposits; most are also textured by sandy-loam traces.
Heading back down to the valley floor, we now arrive at Yountville AVA (located just north of the Oak Knoll District). This is Cabernet Sauvignon and (particularly) Merlot territory, the latter greatly benefiting from the clay-rich alluvial deposits to be found throughout the AVA. While the sub-appellation extends right up into the hills, directly bordering Mount Veeder, most vines are found on the valley floor. I rarely encounter wines made exclusively from Yountville grapes.
Directly east, however, I have often happened upon some superlative bottlings from the much-heralded Stags Leap District AVA. This is where some of the most elegant Cabernets in the entire Napa Valley are produced, despite elevations only reaching 123m. Moderated by marine breezes from the San Pablo Bay, wines from Stags Leap are usually very supple, oftentimes bordering on silky, displaying dark black cherries and capable of aging for decades. Soils are reasonably fertile, containing volcanic gravel-loams that allow for particularly good drainage on the hillsides.
North of Stags Leap District, we arrive at what some would designate the heartland of Napa Cabernet-blends: Oakville AVA. This is where some of the most powerful examples of this noble grape can be found, where Robert Mondavi began his quest of producing world-class wines more than fifty years ago.
Though some marine influence can still be felt from the San Pablo Bay, ripening is fairly simple to achieve on the valley floor; temperatures here are among the hottest in the entire valley. Head to the western (Mayacamas) hills, however, and conditions provide for good drainage and lower fertility—this is where the iconic Harlan Estate is located. For the most part, alluvial fans dominate in the western vineyards, while the eastern portions tend to feature heavier soils intermixed with volcanic deposits—the latter is where Screaming Eagle is located, (arguably) the most sought-after wine, in terms of price, outside of Europe.
North of Oakville, we come to Rutherford AVA, probably the most famous of the Napa sub-appellations. Some would argue that Rutherford represents the epitome of Napa Cabernet Sauvignon: powerful, ageworthy, and extremely ripe. Rutherford is also where Cabernet has been grown the longest, some operations having been established more than seventy years prior. With exception, the best vineyards are found in the west, on the so-called ‘Rutherford Bench,’ with slightly higher elevations and soils comprising gravel-sand deposits and alluvial fans. Over the years, tasters have often detected mineral traces in wine from the bench, referred to as ‘Rutherford dust.’ On the east side, gravel deposits can also be found, though they will often be intermixed with volcanic soils of greater fertility. Like Oakville and Stags Leap, Rutherford wines have no difficulty aging.
Retracing our steps just for a moment, if we head to the hills east of the Stags Leap District, we come to Atlas Peak AVA. By most accounts, the creation of this particular, and peculiar, AVA is the result of one man and his quest to perfect Sangiovese in the Napa Valley: Marchesi Pierro Antinori and his founding of Atlas Peak Vineyards. Unfortunately, results for Sangiovese quickly proved a non-starter for this otherwise legendary individual; but the area has shown reasonable promise as a reliable location for sturdy, sprightly Cabernet Sauvignon. With elevations reaching as high as 792m, soils are largely volcanic in origin and very thin. Breezes from the San Pablo Bay are able to reach here with virtual ease.
Northeast of here lies yet another lesser-known area: the Chiles Valley District AVA. Another outpost for would-be vignerons, Cabernet Sauvignon and Zinfandel have both shown particular promise in this reasonably warm yet cooler winegrowing region. On the valley floor, alluvial soils and clay deposits predominate, while the hillsides show more clay-loam and stony-clay compositions.
By comparison, the Howell Mountain AVA, north and parallel to the Chiles Valley, is much more famous. Historically recognized for its Zinfandel, this isolated sub-appellation is nowadays best known for some of the most elegant Cabernet Sauvignon-blends in all the hills of the valley, particularly the offerings of Dunn Vineyards. Reasonably free of fog at elevations reaching up to 675m, the Howell Mountain benefits from superb day/night-time temperature variations and infertile, well-drained soils, much of which is volcanic and shallow in composition.
Returning to the valley floor, north of Rutherford is the St Helena AVA. A sub-appellation of contrasts, while St Helena is home to some of the largest wine businesses in Napa, the area also boasts a fair number of cult operations. Warmer than Rutherford and the largest of Napa Valley’s towns, Cabernet Sauvignon predominates; yet other grapes such as Merlot and Zinfandel have also fared well. Soils in the south and west are largely based on gravel and clay, while northern soils are more volcanic in origin.
West of here is the Spring Mountain District AVA. Boasting a similar climate to that of Mount Veeder, the sub-appellation benefits from both altitude and proximity to the Pacific Ocean. With elevations reaching as high as 675m, Cabernet Sauvignon and Chardonnay are the main trump cards of the region. Soil deposits are composed primarily of weathered sandstone and shale.
Head north and we arrive at the Diamond Mountain AVA, one of the northernmost outposts of Napa. With elevations reaching up to 530m, the best growers in this remote area, such as Diamond Creek Vineyards, have been those best able to exploit the remarkable diversity of volcanic-based soils to be found throughout this reasonably cool sub-appellation. For my part, I have often thought Diamond Mountain Cabernet Sauvignon to be among the most elegant in this part of California. Good Chardonnay, too.
Finally, we arrive at Calistoga AVA, one of the most recently designated sub-appellations. Encircling Diamond Mountain and serving as the northern continuance of St Helena, this part of the valley benefits from both cool ocean breezes and being almost entirely surrounded by mountains. Cabernet Sauvignon, Zinfandel, and Chardonnay are all found in abundance. Soils are almost entirely volcanic in origin.
So there you have it: the sub-appellations of the Napa Valley in their entirety, a positive sign that Napa winemakers do, in fact, have some interest in the notion of terroir. Of course, in reality the sub-appellations of Napa are nothing like their counterparts in the Médoc, where restrictions of vine densities, yields, grape varietals, and minimum natural alcohol levels are clearly defined. Even in Napa sub-appellations, vintners have a free hand in most of their doings—hell, only 85% of the actual grapes have to come from any specific sub-appellation in order for it (i.e. the sub-appellation) to be included on the label. But at least a sub-appellation like Carneros (cool-climate) or Oakville (hot climate) or Diamond Mountain (elevation) will provide some indication as to how the wine will probably taste. For Americans, greedily laissez-faire as they are, this can be deemed an excellent start.