Some of this, some of that...

In wine, as in many things, what's on the outside isn't always on the inside -- to put it simply, the things that the label advertises is not always what's in the bottle.

Let me explain (from a general US-centric perspective -- other countries do vary, and specific appellations may have different rules).  When you go to the wine store to buy a bottle of 2007 Reserve Napa Sauvignon Blanc at 13.8% alcohol...  all of those things are approximate.

The grape?  Once 75% of the bottle is filled with juice from that grape, the vintner can put anything they want into the bottle.  So your Sauvignon Blanc may well have some Semillon or Muscadelle.  I know of one major producer who's back-label text (which is, as far as I know, completely unregulated) begins with the phrase, "this 100% Chardonnay," despite the fact that their wine tastes severely of Gewürtztraminer -- I suspect about 10%.  Another producer -- Woodbridge, by Mondavi -- will only verify that their Chardonnay is 75% Chardonnay, and the remainder is "a blend of white grapes."  Why would vintners want to fudge the grape?  Well, for one, they don't want to give away their formulas -- and trust me, for the big producers, it's a formula, an attempt to make the same product year-from-year.  For another, consumers seem to self-brand as "I drink Chardonnay," or "I don't like Merlot."  I guarantee you that there's some guy out there right now drinking (or thinking about drinking, if it's early) Silver Oak Napa, saying "I hate Merlot," blissfully unaware that Silver Oak is only around 90% Cabernet, and that the remainder is a healthy chunk of Merlot, with a dash of Petit Verdot.

The alcohol level?  Nope.  There's wiggle room -- it varies from region to region -- but you can go anywhere from +/- 1.5% in Australia (although this may be changing soon to 0.8%), to +/- 0.5% in the US.  Figure that the alcohol level is approximate.  Again, it's to a producer's benefit to estimate the alcohol level -- generally to lowball it.  High-alcohol wines are taxed as "fortified wine," even if there's no addition of alcohol during the vinifiation, and therefore there's a tax break to underestimating the alcohol.  Additionally, in some states (South Carolina comes to mind, but it's assuredly not the only one) anything under a certain alcohol level can be sold in a wine-and-beer licensed retailer (an easier and less expensive licensce to get), while anything over that level is from a liquor-licensed retailer.  Since there are more wine retailers, it makes sense to try and keep your wine in their shops, rather than having it shunted over to the liquor stores.

The appellation?  I mean, as important as terroir is to wine, that's got to be dead-on, right?  Nope.  Once 85% of the juice has come from an appellation, the remainder can come from outside.  It allows vintners to source grapes for their blends that aren't found in a specific appellation, or to find the best grapes they can (ideally this would mean "best-quality," but it often means "best-priced").

The vintage?  Really, c'mon, even the year?  Yep.  Again, depending on the appellation, you're allowed some wiggle room there too -- older wine to add depth and complexity, younger wine to add fruit and youth.  Generally, there's not a lot of wiggle room here -- around 5% is the norm -- but not all the wine has to be from the same vintage.

Other terms -- "reserve," "old vines," even "estate grown" can be subverted.  "Reserve" is a marketing term in the US, nothing more (other countries have different rules -- in Italy and Spain, for example, the term has legal weight).  I know of two lines of wine that make only "reserve" wines, and nothing else.  Not that they're not decent, but the term is suspect.  "Old vines" generally means the vines used in the wine are an average age of 30+ years, and most producers respect that.  Is there a legal standard for it?  Nope.  Is someone out there bottling wine from 5-year-old vines and labeling it "old vines?"  Almost assuredly.  "Estate grown" generally means the grapes were grown on-site, but I know of a producer (in fact, the Chardonnay producer who makes "100% Chardonnay" with a splash of Gewürtztraminer) that labels all their low-priced wines as "estate grown" on the case, even though they make so much wine there must be outsourcing of production (additionally, the "estate grown" wine has a generic "California" appellation.  So, unless the "estate" is larger than any single appellation in California...).

Napa's Terrior

In a discussion with a friend -- an admitted Francophile when it comes to wines -- the topic of terroir came up.  The argument my friend made is that French wines are superior to Californian, because they express the terroir of their home region better.  I argue that there is, in fact, distinct terroir to Californian wines, and will use Napa valley to illustrate the point.  Note that I'm not arguing the superiority of Californian or French wine, just trying to disabuse the notion that Californian wines are soul-less and lack terroir (only some of them fit into that category... and the same could be said of mass-market French, or Italian, or Australian, or Chilean wine.  Anywhere that you produce wine as an industrial product, you'll have soul-less wine with no terroir!).

So, perhaps an explanation of what, exactly, "terroir" is would be in line here, as it's a French term that has no direct equivalent in English.  Basically, the idea of terroir is that the dirt (and climate, and drainage, and level of shade) here is different from the dirt (and climate, and drainage, and level of shade) there, and therefore wine made from the same grapes here will be different from the wine made there.  Ideally, a wine expressing terroir makes someone who tastes it blind immediately go "this is from only one spot on this green Earth, right there."  The idea of terroir explains why, for example, Petrus commands such a high price -- it's grown in a specific point in Pomerol, and there's no place exactly like it anywhere else, and that place happens to grow terrific grapes that express terroir well.

We'll be talking about Cabernet -- it's the grape that made Napa famous, and it's the red varietal that is most arguably the best expression of what a "good" wine from the region is.  Napa Cabernet runs from $10 to "hey, how much do you want to spend?" to "it's completely unavailable unless you're on the mailing list," and that's just for the new releases.  It's the crown jewel grape of Napa.

So, let's look at the AVAs within Napa.  Broadly speaking, they divide into mountainside AVA's (Mt. Veeder, Spring Mountain, and Diamond Mountain near the west, Howell Mountain and Atlas Peak on the east, and the Chiles Valley), and valley floor (everywhere else).  The wines from the mountainsides tend to be a bit less fruit-forward than the valley floor wines, and have more acidity.  The valley floor wines tend to be a bit rounder and more intensely flavored.

Additionally, different AVAs have their own distinct characteristics; Diamond Mountain tends to show off cocoa and espresso, while Mt. Veeder is much more earthy.  Oakville wines tend towards intense, richly textured wines with a hint of mint, while Stag's Leap District is best described as an "iron fist in a velvet glove," with beautiful, velvety tannins.

So what does that mean for someone drinking a bottle of Napa Valley's best?  Simple; if you want big fruit, go to the valley floors.  For wine with more ageability, look to the mountains.  If you find a winery makes a wine from an AVA that has a style you like... you'll likely enjoy the wines from their neighbors!

And, the best argument for Napa having terrior?  Why do you think the cult (and would-be cult) wines concentrate themselves in Oakville -- Harlan, Screaming Eagle, Ghost Block, and Nickel & Nickel all source from there...  The rich, ripe fruit, subtle tannins, and moderate acidity have a lot to do with it.  

Map from Napa Valley Vintners.