Stag’s Leap Wine Cellars

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Stag’s Leap Wine Cellars

Vineyard Articles

The Place Beneath: The "Sweet Spot" of FAY

Over the more than three decades that we have been farming our historic estate vineyards, we’ve learned that small areas within particular blocks consistently produce grapes with unique qualities of flavor and texture. A case in point is FAY Block 8. In its center is an irregularly shaped "sweet spot" that yields fruit of unusual expressiveness, characterized by voluptuous softness as well as concentration. Over the years this "sweet spot" has been a key component of CASK 23.

Although we knew that soil differences within the block probably accounted for some of this variation, we did not learn the deeper story until we had the opportunity to participate in a geological investigation of the Napa Valley.

Over the past four years, geologist Jonathan Swinchatt, author of The Foundations of Wine in the Napa Valley, and David G. Howell, a research geologist with the U.S. Geological Survey, explored the valley’s geologic past and present. Their findings are reported in their book, The Winemaker’s Dance: Exploring Terroir in the Napa Valley, just published by the University of California Press.

At our invitation, the two took a literally in-depth look at our S.L.V. and FAY vineyards as part of their research. Over 90 pits from two to eight feet deep were dug with backhoes, including 39 in FAY Block 8 alone.

We wanted to make more of the style of Cabernet Sauvignon that the center of Block 8 exemplifies with softness at the edges and a complex core. We undertook this research in order to be able to pass on to the next generation the knowledge to be able to produce even better fruit.

According to the two geologists, around eight million years ago volcanic eruptions associated with the tip of the growing San Andreas Fault began to deposit ash and lava over the marine sandstones and shales at the continent’s edge. About two million years ago the valley began to form as earth forces associated with the San Andreas Fault compressed the crust, squeezing the rock layers, causing them to fold and break, and creating the Mayacamas and Vaca ranges that form the valley’s western and eastern borders. The area’s intricate array of bedrock types was further complicated by huge landslides. Weathering and decay of bedrock formed the loose sediments that accumulated over bedrock or were dispersed by gravity and water to form the alluvial fans at the foot of the mountains and the floodplain deposits of the Napa River.

In our own corner of the valley, beneath the volcanic rocks of the Stags Leap Palisades, water streaming from the hills spread boulders, gravel, sand, and silt across what the geologists call the Stag’s Leap Alluvial Fan, which covers most of what is now S.L.V. and FAY. The diversity of ground created by these events became clear when the backhoe pits in our vineyards revealed significant geological differences between areas that, on the surface, did not look radically different. For example, within the Block 8 "sweet spot," boulders up to two feet in diameter lie close to the surface, swept down from the volcanic hills during some huge prehistoric storm. Beginning just a few yards away, outside the spot, the boulder layer lies progressively deeper, covered by layers of finer sediment.

Such knowledge is helping to guide our decisions about how to coax the best possible quality out of every part of these two historic Napa Valley vineyards. What we had already identified by taste has been corroborated by geology. Now we can use that knowledge to help us to expand that window within which particularly expressive fruit can be grown.