SNOW may still threaten and the crocuses may still be sulking, but residents of Virginia's hunt country are dusting off their thermos bottles and retrieving their picnic baskets from the attic. The 1985 Virginia point-to-point races, true harbingers of spring, begin this weekend in Warrenton.

This ten-week circuit is a grueling test for horses and jockeys, but it's no less arduous for the dedicated spectators who attend the races weekend after weekend each spring. It's a time to shape up social skills grown flabby during the winter, and to reaffirm all that is sacred to the hunt country way of life.

Many Washingtonians eagerly look forward to the spring races as informal sociological field trips. Usually no more than a 11/2-hour drive from the city, the meets offer a day of "gentleman's sport" played out against a lush background of bluegrass-covered hills, as well as a rare opportunity to rub elbows with everyone from local bookies to Paul and Bunny Mellon.

Yes, the people-watching is choice. But be warned that it isn't one-sided. You, too, will be duly watched and classified. So here's a brief guide to field observation at any of the approaching point-to-point races.

At the very top of any local social pyramid you will find the Old Guards. They are either descendants or bearers of fine old Virginia names, or immigrants from select areas who have tenaciously outlived the stigma of not being Virginia-born. These are the people who own the secluded estates for which the hunt country is noted. They will arrive in battered, mud-bespattered station wagons or Jeeps with plenty of dog hair on the seats. Both sexes will be dressed in decidedly threadbare tweeds, sensible rubber boots and odd hats decorated with point-to-point badges. If you have any doubts, think of how the Queen Mother would dress to walk her corgis down to the stables.

In comparison to the Old Guards, New People (those who own hunt-country homes but have just begun their long social novitiate) and those from Away (weekend guests of New People) are exceedingly easy to spot. They arrive in shiny Jaguars, antique Bentleys, pristine Porsches and dressed in various high-fashion outfits ranging from Ralph Lauren faux rustic to decollet,e cocktail dresses. The women nearly always wear three-inch spike heels that sink into the soft turf up to the soles, much to the smug delight of Old Guard matrons. Female New People also sport important Ascot-type hats while their male counterparts wear natty English caps.

Local Good Ole Boys arrive in dented Jeeps and pickup trucks and may cause some temporary confusion if parked in the immediate vicinity of Old Guards.

Much information may also be obtained through careful observation of the obligatory tailgate picnics. Old Guard picnicsfeature tartan blankets as table cloths and have centerpieces composed of a handful of daffodils jammed into an empty bourbon bottle. New People, on the other hand, vie with one another to produce the most precious display. Tailgate totems include Pratesi linens, orchids in Lalique crystal and an overabundance of silver.

If you have any further doubts about who's who, just check the contents of the tailgate and the manner in which it is displayed. True hunt-country gentry place the emphasis on copious liquid refreshment: Bloody Marys, bourbon, vodka and beer. There will also be some fried chicken, a few deviled eggs and a handful of potato chips, as an afterthought.

Preferring to consume champagne and wine spritzers, New People cook their hearts out. This allows Good Ole Boys, used to a life of rural isolation, to observe such exotic fare as tortellini salads and flamb,eed kiwis once a year.

Everyone brings the family dog, though a brace or a small pack carries more status than the lone pet. They are leashed for the day lest Old Guard Labradors and Jack Russells tangle with New People Shar Peis.

In the meantime, horses and jockeys are risking life and limb galloping over the impeccable grass courses. The initial races are "flat," short sprints with no jumping. Interest builds when the horses begin to race over fences. This is a grueling sport for both horse and rider.

Falls, unfortunately, are quite common. When they occur, the jockeyless horse will frequently continue to race, going over all the jumps and eluding efforts to catch it. A jockeyless horse that comes in first, however, is disqualified, a rule that has angered many a bettor.

Yes, there often is discreet betting, although it's very much against Virginia law. Would-be wagerers simply go to the paddock area where they find several well-known entrepreneurs posting odds on portable chalkboards. These gentlemen do a lively business taking ten-dollar bills and issug scraps of paper with horses' names on them.

Every so often, a local judge will send a sheriff to attempt to capture one of the offenders and remind the public of the illegality of the operation. There is always much merriment as the adequately forewarned bookmakers flee nimbly, chalkboards under arms, followed by the sheriff. No one bets on the outcome of this race.

Toward late afternoon, when the Bloody Mary mix begins to run out and the lines at the portable toilets become intolerably long, people pack up the debris in their station wagons and head for home. Another point-to- point race has come and gone. Another hangover is perhaps about to begin. Ah, spring. GETTING A JUMP ON SPRING

The Virginia point-to-point circuit gets off to a running start this weekend and stays the course every weekend to April 20. For serious tailgaters, reserved parking right next to the course is available for $35 to $50 per car. It's usually sold out to the locals in advance but you can always try calling, at least 10 days ahead. General admission, usually $5 per person, allows you to park your car and walk a short way to the course. Here's the schedule for the first three weeks:

FEBRUARY 23/24 -- Casanova Hunt. First race is at 12:30 on Saturday; Sunday at 1:30, Hunter Pace Pairs race. Held at Mt. Sterling Farm in Warrenton. From Washington take I-66 to Gainesville; go south on U.S. 29 to left on Route 605 for about 3 miles; race course is on the right. For information, call Will O'Keefe, 703/439- 3669, 439-8089 evenings.

MARCH 2 -- Rappahannock Hunt. First race is at noon, in Sperryville. Call 703/547-2011 or 703/635-4873.

MARCH 9 -- Blue Ridge Hunt. First race is at 12:30 in Berryville, Virginia. Call 703/837-1719 or 703/837- 2262.