The Rockpile American Viticultural Area (AVA) on the northwestern edge of Dry Creek Valley in Sonoma County is tiny. The designated area includes about 15,000 acres, but most of them are vertical; planted acreage is about 165 acres, with another 50 or so plantable, at least in theory. Eight vineyards make up the Rockpile Grape Growers Association; about 15 wineries -- none of them located within the AVA -- bottle wines from the area.
The wines are something else: big, flavorful, intense reds, prominently Zinfandel but also Cabernet Sauvignon, Cabernet Franc, Malbec, Syrah, Petite Sirah, Petit Verdot, and a few others varieties. The wineries that deal in Rockpile fruit include some very serious names: Rosenblum Cellars, Carol Shelton, JC Cellars and Seghesio, for starters. A chance to taste though lots of them yesterday afternoon at Rock Wall Winery in Alameda -- the new startup for Kent and daughter Shauna Rosenblum, now that the mothership has been sold to the Diageo drinks conglomerate -- was a treat, reinforcing the impression I already had from random drinking that there's something special about the place.
Elevation and climate have a lot to do with it. The AVA's boundaries mean that the lowest point is 800 feet above sea level; other vineyards reach up to 2100 feet. That limits Rockpile's fog quotient, leads to average temperatures 15 degrees or so cooler than nearly Dry Creek, and invites constant, gentle breezes that reduce disease pressure on the vines. Add very well-drained, hillside soils, and Rockpile can ramp up the intensity without ratcheting up the sugar and alcohol indefinitely.
So much for the infomercial. I had a chance to talk with several growers and winemakers, and discovered some intriquing things.
First, under the radar, a certain Rockpile grower is about to plant white grapes -- yes, the ones that are not red -- thereby breaking Rockpile's version of the color line. He told me not to mention his name.
Second, I got the scoop on Jeff Cohn's (JC Cellars) experience isolating yeast strains. Jeff is the one who came up with the strain now known as RP-15 (you can guess what the RP is for) from Rockpile fermentations. It's a hot item in the yeast world, on everybody's trial list this year (mine, too); it makes for a strong fruit impression and handles 17% alcohol.
So I asked Jeff if I would have to pay him an additional royalty every time one of those yeast cells reproduced in my garage. Alas, no, he's not getting a cent out of it. Jeff is a first-class winemaker but, by his own estimate, not a world-class businessman. But just wait till he isolates the next one.
Finally, for you fans of terroir, Rockpile turns out to be a fascinating case. The soils, elevation, and natural climate factors add up nicely, and the area has had grapes planted on and off since the 1870s, though the main attractions until recently were sheep farming and hunting clubs. Then in 1982, the US Army Corps of Engineers finished the Warm Springs Dam, creating Lake Sonoma, 200 feet deep in some places, with more than 2.500 acres in surface area. Lake Sonoma wraps around Rockpile like a horseshoe, moderating temperatures and creatina an inversion layer that sucks fog out of the vineyards and down to the lake.Adding Lake Sonoma to the mix was the final capstone in producing the unique set of "natural" factors that make for such distinctive wines. In other words, man-made terroir.