The French have had a thousand or more years to map out and subdivide their grape-growing regions, to determine which grapes grow best in which spots—and even as they seem to slide into spiritual and economic malaise, they can at least be proud that no country makes finer wine. Viticulturally speaking, the map of California is still being drawn; trial and error, coupled with geological and meteorological data, is gradually helping to refine our sense of regionality, of location, location, location as a key determinant of wine character.

It’s only in the last 20 years or so that the West Sonoma Coast has been recognized as a superb region for Burgundian varietals of Pinot and Chardonnay, with Hirsch Vineyards, which I wrote about in my last column, playing a pivotal role in that discovery. Wines from David Hirsch’s vineyard made by Ted Lemon, Burt Williams and Steve Kistler inspired a new generation to explore the rugged, sparsely populated ridges along the coast.

When Nick and Andy Peay started scouting the West Sonoma Coast for likely-looking vineyard land in the mid-’90s, there wasn’t much competition and land prices were low. “We’d tasted the Hirsch wines and we liked the florality and the acidity,” Andy told me when I visited their remote vineyard a few miles from the coast last month. They both liked Burgundy and wanted to make wines like those, more restrained and less fruity than those from Carneros — at that time the hot area for Pinot and Chardonnay.

Wine was served at dinner when the brothers were growing up in Ohio, but Nick’s interest was really piqued by his Bowdoin College roommate, Hugh Davies, whose family owned Schramsberg Vineyards in Napa. After graduation, Nick went west with Mr. Davies to work at the winery, which led to other winery jobs and graduate study in oenology at the University of California, Davis; younger brother Andy, after spending two years in New York working for Chase Manhattan, studied at Berkeley and got increasingly passionate about wine under the influence of his older brother.

“We started scouting the Sonoma Coast in 1994 and 1995,” Andy said. “We wanted to be pioneers. We got the U.S. Geological Survey maps and started driving around.” They were looking if anything for even more extreme terrain than Mr. Hirsch’s property, which was above the fogline. “We were looking for bracken fern and Spanish moss. Water is a big problem on these ridges, and if you have ferns, you have water, and if you have moss, you have fog.”

Eventually, they found an old farm surrounded by redwoods about 4 miles from the Pacific that still feels, more than 15 years after they found it, like it’s near the end of the earth. Happily for the brothers, a caretaker living on the property had kept detailed temperature records for years. “He handed me this spiral notebook,” said Nick, “with detailed temperature readings.” Nick—who is a true geek, and loves nothing better than to talk rootstocks and diurnal swings—clearly cherished this particular document. A bonus was the 1906 farmhouse on the highest point of the property, which they planted with Pinot Noir, Chardonnay and Syrah in 1998.

Nick, who presides over viticulture (and whose appearance and wry sense of humor put me in mind of a young Michael Keaton), spends a good part of the year on the remote property. It’s more than an hour west of Healdsburg, which their winery is near, and more than two hours west of St. Helena, where Nick’s future wife, Vanessa Wong, was living when they began dating. She was working as a winemaker at Peter Michael, after studying at UC Davis and apprenticing in Bordeaux and Burgundy. Vanessa became the winemaker for Peay Vineyards in 2001. Andy, who seems the more gregarious and extroverted of the two brothers, handles sales and promotion for the winery from his home base in Berkeley.

The Peay wines soon developed a following—as did the wines made from Peay grapes by Williams Selyem and Failla Vineyards—and helped to burnish the reputation of the West Sonoma Coast as a source of distinctive, refined and aromatic wines, especially Pinots and Chardonnays. Peay has also gained a following for its Northern Rhône varietals, notably Syrah and Viognier. Flowers, Marcassin and Failla were among the other pioneers that demonstrated the potential of these remote coastal ridges, though it turns out the word “coast” can be very broadly construed.

In 1987, the Alcohol and Tobacco Tax and Trade Bureau had created a Sonoma Coast AVA, or American Viticultural Area, that encompassed more than 500,000 acres of land and included vineyards more than an hour from the coast—an area so large and climactically heterogenous as to be almost meaningless.

Many informed observers have started speaking of the true Sonoma Coast, or a West Sonoma Coast. “Wines grown on the true coast possess an undeniable link to their maritime origins—a link wines growing further inland lack,” said Matt Licklider, who makes excellent Pinots and Chardonnays under the Lioco label.

“That the appellation is so huge and covers areas with a 20-degree temperature variation and very different soils makes a farce out of the idea behind appellations,” said Andy Peay. Recently, the area that includes Hirsch, Flowers and Marcassin and other great sites got its own AVA, Fort Ross-Seaview, and further subdivisions are inevitable, as in Burgundy.

A few years ago, Mr. Peay and some of his neighbors (Failla, Freeman, Littorai, Freestone and Red Car) formed the West Sonoma Coast Vintners, which now has 40 members. Even within this cool coastal area, there is diversity. Higher-elevation vineyards above the fogline produce richer wines, while Cobb and Rivers-Marie in suburban Occidental, a good hour and a half south of Annapolis, are producing brilliant, crisp Pinots in a slightly warmer microclimate than Peay’s. Cobb Wines is a father-son venture founded in 2001 by David and Ross Cobb; son Ross also has a day job as winemaker at Hirsch Vineyards. Rivers-Marie is owned by superstar winemaker Thomas Rivers Brown (who makes Maybach, Schrader and numerous other wines) and his partner, Genevieve Marie Welsh, who recently acquired the Summa Vineyard in Occidental, from which Burt Williams and Ted Lemon of Littorai made legendary wines. Their own Summa Old Vines, made from 5 acres of gnarled vines planted in 1979 in Occidental, has quickly become a cult classic. The couple paid $2.5 million for the vineyard, some 15 years after the Peay brothers acquired their own vineyard for about $4,000 an acre—an indication of the vineyard’s renown, but also a sign of just how hot the cool-weather West Sonoma Coast has become.