The expressions were serious, the negotiations intense. Douglas Cohen, recently 12, had come to buy a skateboard.

His father, Harvey, had temporarily forsaken his practice of law to stare in bewilderment as his son discussed the viability of red pads, the advantages of Fiberflex and the effect of road tar on yellow yo-yo wheels.

In the end, his son's decision turned less on logic than on other standards of choice. "You know that red-haired kid that comes in here all the time who's about my height?" Dough asked Tim Carrington, the manager of Skateworld in Alexandria. "Do you have a board like his?"

Carrington signed. "In the end, they usually get what's cool," he said. "And what's cool changes about every six weeks."

In California, where extravagance is raised regularly to religious levels, skateboarding has assumed the intricate and elaborate proportions of a cult. But in Northern Virginia, its suburbs heavy on the kids, concrete and affluence on which the sport depends, skateboards have become the ultimate childhood status symbol.

Those who buy them are rich enough to afford a toy that usually cost between $60 and $130, and yound enough, in body or spirit, to believe in their own invulnerability to catastrophe.

And, as a $300-million-a-year industry, skateboards are also big business, one that is adding a new feature to the local landscape - skateboard parks.

Until recently, skateboarding in the area was confined to sidewalks, neighborhood streets, and certain mysterious places that aficionados spoke of interms normally reserved for hallowed ground - a celebbated embankment near the Pentagon, certain drainage pipes in Anacostia, a wooden ramp in Burke, to which, it is claimed, skaters came all the way from North Carolina to conquer.

The last few months, however, have seen the opening of several acres of rolling concrete waves where skaters can work on perfecting the nuances of the gorilla grip while the parks' young owners sit bemused by even greater ambitions. There are, it seems, asphalt empires to be made.

"It's incredible," says Richard Evans, whose skateboard park. Skate Mall Wall, looks out on the vast reachers of the Springield Mall shopping center. "The market's just opening up here, the possibilities are limitless.

Evans is 28, a lean body in taded jeans with a network of the fine scars on his face and a permanently bent finger to show for his own years on a skateboard. Talking faster than a runaway skateboard can speed down a drainage ditch. Evans surveys his quarter-acre of hills, mounds and culverts that will eventually, he says, become four acres of challenges to parental peace of mind.

Evans designed six skateboard parks in North Carolina before expanding his horizons to Northern Virginia, and sees Skate Mall Wall as the first of seven that he plans to open in the area.

"The only thing that will keep skateboarding alive is competition," Evan says, and he envisions a "superbowl of skateboarding" where teams formed around each of his future parks compete aganst each other in the old thrill of victory, agony of defeat motif.

Right now, competition is coming from a different quarter. Down ths interstate apiece, in Alexandria. 23-year-old Tim Carrington looks out on the same rain that has put a damper on Evan's spirits and hungers for the same market.

Attended by a raucous troupe of temporarily greounded 12-year-olds. Carrington said that Skateworld, the Alexandria park, is the first of four that he plans to open in the Maryland and Virginia suburbs by next spring.

According to Evans, Carrington was in such a hurry to open ahead of him last August, that he opened his park before all the lights had been hooked up and with only a coffee can in which to collect the $1.50 entrance fee and equipment rentals.

"Sure," Carrington says. "Why not?" A recent graduate of Villanova University, Carrington forsook a broker's job in New York City to manage Skateworld, which was built by National Construction Company, a swimming pool manufacturer.

"There's no comparison between their park and our park," Carrington said. "Ours has more to offer. His (Evans) is really too dangerous for the average person, but of course I'm blased."

"Their isn't challenging enough," Evans says of Carrington's park. "It's just sour grapes because we're more popular than they are."

Both Carrington and Evans have "pro shops" in their parks that sell skateboards and all their myriad parts and in-house experts to dazzle the masses and a plethora of plans.

There are plans for skateboard clubs at local schools, intramural skateboarding, lessons for the uninitiated and trophies for experts in all age groups.

"The beginners will take home their little trophies and they'll get all excited," Evans said. "It's gonna be just like soccer and little league base-ball."

Maybe it will, but for the time being, skateboarding is still something of an outlaw art, its grace and beauty heightened by the ever-present possibility of the board's betrayal.

It's an esoteric world as well. It's longuage nearly incomprehensible, its mythology rich with teenaged heroes who have found fame and fortune in a world of nearly perpetual motion.

I hear my son talking about it and I don't understand a word he's saying," said one mother as she watched her son work on a 180 degree turn. The incomprehensibility, of course invests skateboarding with added value in the curiouss would that 12-year-olds inhabit, providing them with another defense from adult intrusions.

Skaters look scornfully at novices who ask for explanations of such terms as power slides and flyouts and they shriek with delight at questions that betray total ignorance of the sport's finer points.

They shrug with elaborat nonchalance when asked why it is they spend long hours defying danger broken bones and gravity on four wheels and a piece of wood or fiberglass. The meaning, it seems, is merely in the motion.

Thus 13-year-old Mike Marks of Mount Vernon saves hil launch money every day and spends 45 minutes on a bus in order to test his skill at Skateworld while Erich Leslie comes all the way from Dale City to check out Skate Mall Wall.

And 12-year-old Chris Peery spends long hours in the gathering dusk perpendicular to any wall he can find. "It's something to do," he says with a shrug that shakes the blond hair out of his eyes. And what did he do before he started skateboarding? "I don't know. Just be bored. I guess."

They talk about the speed and they talk about the challenge, but they don't talk about the danger much except insofar as it enhances the ride's excitement.

At the parks, the skaters are required to wear helmets and knee and elbow pads and to prove theri skills before they are allowed into the more advanced areas where the curves are sharper and the walls are steeper.

Both parks say they have had some broken bones, but nothing that either the mangers or the skaters seem to consider serious. "Fingers and wrists, mostly," says Rick Evans. "Things that generally come from people doing something they shouldn't. We do everthing we can to protect them except stand underneath them when they fall."

In fact, according to a recent report by the Consumer Product Safety Commission, riding a skateboard in one of the concrete moonscrapes designed for the purpose significantly lowers a skater's chances of getting hurt in a sport that is now second only to bicycle riding in causing injuries but with only one fourth the riders.

Neither the skaters nor their paretns seem undully upset at the possibility in their kid to skate and he's already got a cast on his arm," Evans said. "Or you'll ask a kid to rate him self and the father will say 'oh, he's advanced, no question about it.'"

"I figure if he doesn't break his arm this way, he'll probably just do it some other way," said Harvey Cohen. The winning skateboard combination, then in the process of being assembled would cost over $80.

"This is what they're into," Cohen said. "If this is what he wants, OK."

He turned to his son "Well," he said. "Is this going to be the best board on the block?"