THE DEBATE over the potential for aging of California's top-quality cabernet sauvignons will never cease. Opponents argue that California cabernet, while impressively grapey, rich, full and tannic when young, does not improve and develop complexity in the bottle when it is cellared by collectors. They feel that only cabernet sauvignons made in Bordeaux develop significant complexity and improve from extended aging in a wine bottle.

California's growing climate is too hot, the soil too rich, the vines too young and the wines too deficient in acidity, they say, to produce wines with the character and substance to improve measurably. Consequently, followers of this line of thinking favor drinking up one's California cabernet sauvignons before they turn 10 years old--an age when most good bordeaux are just beginning to provide pleasurable consumption.

Supporters of aging the top California cabernet sauvignons claim such arguments are ludicrous. They point out that the majority of the new wave of California cabernet producers have not even been in existence for 10 years--the minimum time necessary to pass judgment on whether their wines improve in the bottle.

The flash point for these two schools of thought occurred at a recent tasting of California cabernet sauvignons from one of Napa Valley's oldest and most respected producers. Mayacamas Vineyards, located on the Mt. Veeder Peak, is the highest winery in Napa Valley, and has been producing cabernet sauvignon since its inception in 1941. The vineyards are well established, and the mountainside location is considered by viticulturists as one of the best for producing cabernet sauvignon grapes that retain good acidity and achieve maximum ripeness.

While I have traditionally subscribed to the rule that most California cabernet sauvignons get older, but rarely get better, such a generalization hardly accounts for the phenomenal aging attributes of older cabernets from Beaulieu, Ridge and the pre-1970 Inglenook "Cask Series" wines. More recently, efforts from such wineries as Joseph Phelps, Robert Mondavi, Sterling, Caymus, Chappellet, Burgess and of course Mayacamas, have demonstrated at least the likelihood of modest aging potential.

Of all these wineries, Mayacamas produces the most intense and tannic wines, seemingly requiring extensive cellaring to shed their tannin and develop harmony. So rough and astringent are the cabernet sauvignons of Mayacamas in their youth, that some observers have compared them favorably to those of Chateau Latour in Bordeaux, a property long noted for its great wines, which frequently require 20 to 30 years to mature.

The tasting of Mayacamas cabernets included recent youthful vintages such as 1978, 1977 and 1976, as well as older rare vintages such as 1970, 1969 and 1968. As the tasting notes so clearly indicate, there is plenty of ammunition for both schools of thought in the aging debate.

The tasting was not a typical vertical tasting. In most vertical tastings, the wines are from the same producer, and are served in succession, proceeding from the youngest to the oldest. Some vertical tasting groups categorize the wines by richness and concentration, pairing big, highly ripe vintages together, and serving them after lighter, less concentrated vintages. This prevents a big, ripe, highly concentrated tannic wine from overpowering a lighter, more elegant wine at such a tasting. The tasting can be either blind (the identity of the wine's vintage is not known) or unmasked (all wines and vintages are known to the tasting group).

This particular tasting was blind at the request of the majority of the group, and the wines were served in the inexplicable order of 1969, 1973, 1968, 1974, 1976, 1975, 1978 and 1970. For curiosity, and to keep the tasters on their toes, the collector who held the tasting threw in three mystery wines: a 1969 Freemark Abbey "Bosche'" Cabernet Sauvignon, a 1969 Vidal Fleury Co te Ro tie, and a 1970 Chateau Montrose. Two of these three wines stood out, and were easily recognizable as lacking the style of the Mayacamas cabernets. The Freemark Abbey 1969 was slightly sweet, curiously minty and tangy on the palate, and generally held to be a pleasant, but average quality wine with some evidence of fatigue. The 1969 Vidal Fleury Co te Ro tie had been badly stored and was flawed, whereas the 1970 Chateau Montrose seemed closed in, big, rich and tannic, and surprisingly similar to several of the Mayacamas cabernet sauvignons, although it did possess a more austere character. To most people's surprise, no one picked it as being French or even out of place in the vertical tasting of the Mayacamas cabernets.

The only Mayacamas cabernet sauvignon that had developed what would be considered a classic, mature cabernet sauvignon bouquet was the 1969. It exhibited an interesting, spicy, cedary, blackcurrant aroma that married nicely with the ripe, savory flavors. Every other Mayacamas cabernet, despite stylistic differences because of the particular vintage, had the following characteristics in common: a dark ruby color; a briary rich, cassis, oaky aroma; a rich, full-flavored viscous feel on the palate; and significant amounts of tannin, acidity and body.

The favorites in order of group preference were the 1970, 1974, 1973 and 1976, with the 1975 and 1977 receiving the lowest ratings. Personally, I would have given an edge to the 1973 and 1974, followed by the 1970, 1968 and 1978. As much as most people liked the 1969, the wine was ranked fifth in terms of group preference. I felt the 1976, generally well-received by the group, was too massive and tannic ever to develop properly.

The debate over the evolution of a great California cabernet sauvignon in the bottle, such as Mayacamas, can hardly be settled by one tasting. However, as impressive as these wines were, many a diehard enthusiast of the big, tannic ripe style of cabernet sauvignon, so brilliantly exemplified by Mayacamas, must be wondering whether such wines will ever be enjoyable to drink.

Certainly the best of them, such as the 1970, 1974 and 1973, are years and years away from maturity, and one would be a fool to speculate that these will either fall apart or develop into majestic, harmonious, complex wines. In any case, none of the big wines had lost enough of its massive tannin to qualify for pleasurable imbibing at present. While a few tasters pointed to the highly concentrated fruitiness of the wines, the bouquets of even such impressive wines as the 1973 and 1974 had not developed since I had first tasted them back in 1976 and 1977. Keep in mind that both wines are now approaching 10 years old, and even the toughest, most astringent bordeaux has usually developed quite a bit of bottle bouquet by that age.

Do the finest California cabernet sauvignons develop and improve in the bottle like their bordeaux counterparts in France, or do they just slowly lose their fruity intensity and tannin without ever becoming complex or more interesting? For the very finest California cabernet sauvignon producers, it is still too soon to pass judgement.

Mayacamas cabernet sauvignons are available locally, and generally retail at very high prices, usually $18 to $25 per bottle.