McMinnville, Ore. — Blame the volcanoes of the Northwest that sent so much lava roaring through this valley about 16 million years ago and set the stage. Or blame the glaciers of Montana for forcing floods, about 14,000 years ago, that carried in so many tons of rich dirt.

Or you could just blame David Lett. He was the 25-year-old who rolled in from California 43 years ago with a trailer full of vine cuttings and a crazy dream about something called pinot. And now the Willamette Valley is never going to be the same.

After spending most of the 20th century as a haven for hazelnut growers and turkey farmers, this region, about an hour's drive south of Portland, now belongs to the pinot grape and those who admire it.

From the Dundee Hills you can see the trained vines march across the landscape, row by row, like a green invading army or the cast of China's Olympic ceremony. About 275 wineries do business here, joined by burgeoning numbers of tasting rooms, restaurants and lodgings.

Oregon still produces most of this country's hazelnuts, also known as filberts. But ever since winemaking started here in the late 1960s and early 1970s, the way of the grape has been ascendant.

For anybody accustomed to California tasting rooms, this is a different sort of wine country — cooler than the vineyards of Napa or Sonoma or Santa Ynez or San Luis Obispo County; more suited to small-volume operations; and without a single big, fancy hotel.

Here for three weekdays in September, I paid $55 a night for a tiny hotel room (bathroom down the hall) and $20 a day for a rental car (Thrifty, at the Portland airport). I dined without reservations at well-regarded restaurants. I drank a lot. And one morning, I spent two hours on the back of a Tennessee walking horse, gliding down those vineyard rows and ducking under filbert branches with guide Jake Price. Twice we stopped, tied up the horses and sauntered into a tasting room for a nip.

PINOT NOIRS AND CHARDONNAYS FLOURISH IN WILLAMETTE VALLEY, 'THE NEXT NAPA'

The Willamette Valley is about 100 miles long, with six sub-appellations, each offering its own microclimate.

This is "the next Napa, no doubt," says John Stuart, the owner of Abbey Road Farm who arrived from Las Vegas five years ago and raised a few eyebrows by building five luxury guest suites inside three old grain silos.

Of course if you ask a longtime Oregonian about the Napa thing, you're likely to get an earful on how this will never be another Napa but something kinder, gentler and more concerned with substance than style.

But the rest of the world is certainly here, including the French. Domaine Drouhin Oregon, a satellite of the revered winemaking Drouhin family of Burgundy, has run vineyards and a winery here since 1987. Its tasting room opened in 2004, and it's gone Oregon eco-native: In August, the winery added a large array of solar panels.

If you get here this month, you may catch the last of the year's warmer, drier weather, and you're bound to get a glimpse of the grape harvest. At Thanksgiving, you'll find the valley buzzing with wine-soaked special events. Then again, if you wait until spring or summer, when most visitors arrive, you'll have the comfort of milder weather and extended tasting-room hours. If you treat the Willamette Valley as a day trip from Portland, you'll miss a lot.

NOT JUST FOOD AND WINE

I based my wanderings in McMinnville, the seat of Yamhill County. Amid the restaurants and shops in the city's old downtown, the McMenamin brothers, creators of a brew-pub empire in Oregon and Washington, have playfully rehabbed the 1905 Hotel Oregon into a raffish hangout with bar and restaurant below, 42 rooms above and a bar and patio on the roof.

The biggest attraction in McMinnville proper is the Evergreen Aviation & Space Museum (open daily), which has an Imax theater and scores of aircraft, including the Spruce Goose, the enormous wooden plane built by Howard Hughes in the 1940s. If you never managed to see it during its years neighboring the Queen Mary in Long Beach, here's your chance.

From McMinnville you also can make a day trip to the coast (Lincoln City is about 50 miles southwest of McMinnville), hike in Silver Creek Falls State Park (53 miles southeast of McMinnville), book a balloon ride, take a daylong wine-country tour, gamble at Spirit Mountain casino in Grand Ronde (about 18 miles southwest of McMinnville) and browse for garden wares and nursery items at Red Ridge Farms in Dayton.

Or ... you can head to Nick's Italian Cafe, a sort of winemakers' clubhouse since it opened in 1977 and make for the comfortable bar area in the back.

FIRST PINOT NOIR

Thirsty yet?

OK. The first tasting stop is a not-especially-scenic former poultry plant on Northeast 10th Avenue in Dundee. This is where Lett and his wife, Diana, founded Eyrie Vineyards in 1966. David Lett arrived in Oregon by way of UC Davis and planted the first Pinot Noir and the first Pinot Gris grapes here. In those first years, he paid the bills with his day job selling textbooks, while his wife worked as a teacher.

"Back then," says son Jason Lett, 38, who took over Eyrie when his father retired in 2005, "you could borrow money for a prune evaporator, a walnut-drying barn or a turkey shed" — but not to open a winery.

Today, so many winemakers have followed Eyrie's lead that the neighborhood is known as the "Pinot Ghetto." Two years ago, Eyrie opened its modest tasting room. It holds about 20 people, and tasters pay $5.

(How deeply is Eyrie admired around here? Among the 90 or so Pinot Noirs on the wine list at Nick's, the costliest is a bottle of Eyrie's 1976 South Block Reserve, priced at a cool $650.)

At Domaine Serene in Dayton, owners Ken and Grace Evenstad invested millions in making and promoting their estate-grown Pinot Noirs and Chardonnays, and in 2005 they opened a tasting room on grounds as grandiose as Eyrie's are humble. The cost to taste is $15.

Just a short stroll from Domaine Serene stands the Wine Country Farm, which includes a bed-and-breakfast with nine rooms. This is where Price, owner and chief guide of Equestrian Wine Tours, begins his $50-an-hour trail rides.

McMinnville (population about 30,000) and Newberg (about 22,000) are among the biggest cities outside of Portland in the Willamette Valley, but if you're out tasting, you'll soon find yourself in Dundee and Dayton, whose slopes hold many of the area's most coveted vineyards (including those of Domaine Drouhin, Domaine Serene and Eyrie).

Some of the region's best food and drink can be found in Dundee, in a huddle of upscale tasting rooms (Ponzi Vineyards, Argyle Winery) and restaurants (Tina's, the Dundee Bistro) flanking the most congested, one-lane-each-way stretch of 99W.

The Ponzi family was among the area's winemaking pioneers beginning in 1970, and Argyle has won much acclaim with the sparkling wines it makes from Pinot Noir and Chardonnay grapes. And at the Dundee Bistro (owned by the Ponzis), the golden corn beignets with Oregon Bay shrimp made me very, very happy.

In your tasting-room rounds, you're likely to pass through Amity and Yamhill and Carlton, too. In Carlton — which since 2003 has grown from a handful of tasting rooms to 18 — I tasted a few wines at the recently opened Cliff Creek Winery tasting room on Main Street, and then a few more at the Carlton Winemakers Studio, where nine wineries offer their wares at the edge of town in a 2002 building full of green features.

I never did find time to make that day trip to the coast, nor did I get to all the wineries and restaurants I wanted to. But really, on a trip like this, that's exactly the problem you want. So thank you, volcanoes; thank you, glaciers; and thank you, Mr. Lett.