Day 5. By this stage, our small group of four had begun to develop quite a bond. And there had been no arguments or cross words. Just a lot of banter. In fact, my travelling companions had amassed enough material to take me down, if ever they were to choose to share indiscreetly. But there is a rule: what goes on in the hot tub time machine of a vehicle we were journeying in, stays in the tub.

The day began with a few hours in the company of Kevin Pogue (pictured, top), who is a geology professor at Whitman College in Walla Walla. Kevin took us on a tour, showing us the different terroirs, and explaining the large-scale geological events that have formed the various soils in eastern Washington. This was really interesting, and deserves its own post.

Kevin also showed us the new appellation in Walla Walla, called the Rocks. Or, to give it its full name, the Rocks District of Millton Freewater. He was involved in setting this up, and it became an AVA earlier this year. It is a pretty homogeneous AVA, with 97% of the 4000 acres sharing the same soil type. It’s basically an alluvial fan of the Walla Walla River, where the river leaves the Blue Mountains and enters the Walla Walla Valley. And this is the complicated bit: Rocks is entirely in Oregon, but is part of the Walla Walla AVA, which is shared between Oregon and Washington State. So a Washington State winery making a Walla Walla wine from the Rocks can’t label it Washington State, but because the winery is out of state, it can’t really be labelled Oregon, either. Currently there are 300 acres planted, and as you can see from this picture of Cayuse’s vineyard, it’s a distinctive-looking terroir.

From here we went to a very different terroir. Kevin showed us the typical deep sandy/silty sediment that was deposited by massive flood events 10 000 years ago and before. These fine sediments, many of them blown by the wind (loess) are the typical top soils in eastern Washington, and they are very low in organic material: they’re young, and there’s so little rain here. They’re known as exotic soils, because they don’t belong here, and are unrelated to the parent bed rock, which is a huge thick layer of basalt (volcanic origin).

The next stop we were shown was quite different. It was the Ferguson vineyard at 1400 feet, which is a very thin layer of loess over the top of 15 million year old basalt. This was above the flood layer, so doesn’t have the same sediment deposits.

Finally, we looked at a new, promising area for viticulture, which is the cool-climate south fork of the Walla Walla river. Kevin is working with a land owner here to assess the potential for vines.

Then, Leonetti. One of Walla Walla’s pioneers, and a real success story. It was started by Gary Figgins (above), back in 1977. Gary had been friends with Rick Small, and the two of them were army reserves together. Trips down to Napa got them thinking that they could grow grapes in Walla Walla, so Gary started Leonetti and Rick started Woodward Canyon.

We spent time with Gary’s son Chris (above), who now runs Leonetti. He’s a really thoughtful guy who’s working on farming soils, not just vines, and is interested in soil microlife. He also changed the style of the Leonetti wines when he took over, bringing them back a bit from the extremes. They’re now superbly polished but elegant with it. Their deserved success has meant that there’s now a four-year wait to join the mailing list to buy them.

We were off to fellow pioneer Woodward Canyon for lunch and a tasting, with Jordan Dunn-Small and Sager Small, who are the kids of founder Rick. The treat here was a chance to taste the 1999 Artist Series Cabernet Sauvignon, which had aged really nicely. It was noticeably lower in alcohol than the current wines. ‘We want the wines to be full and bright but not overly alcoholic,’ says Jordan. ‘We are definitely working on it, and trying to figure out a good solution.’

The next visit was super-exciting: Gramercy Cellars with Greg Harrington and Brandon Moss. I was so thrilled by the detail, purity and elegance that these wines showed. Syrah is the real focus here, and the Gramercy Syrahs have an almost Burgundian feel to them. I especially liked the Lagniappe and John Lewis Syrahs from 2012. Pretty much everything is fabulous here.

Then it was time for dinner. We dined with Marty Clubb and his daughter Rebecca, from L’Ecole 41. They’re quite famous for their inexpensive but tasty Semillon, which sells for just $15, and is delicious. Their Chenin Blanc is also lovely. At 45 000 cases annual production, L’Ecole 41 is the 12 largest winery in the state, which shows how small scale some of the producers are. We tasted two of the single vineyard Cabernet Sauvignons: the second vintage of the Ferguson Vineyard, 2012, and the 2012 Perigee from Seven Hills Vineyard. Both are dense and vivid, needing time to develop and show their best, but they are very promising.