If one is a cyclist, a jogger or just seeking that peaceful green and gurgle of water that Henry Thoreau touted so masterfully, then in the park is the place to be on any weekend, but especially a Memorial Day weekend when the citizenry has been thinned by the lure of the nearby ocean.

In the city's parks and out there on the C & O Canal towpath, among the verdant shadows, people become their true selves. Particularly, the cyclists, who seemed to have saved their work-week flair for a long weekend's two-wheeled splendor.

Teen-age cyclists in groups whiz by, bobbing and weaving in graceful sweeps across the pathway, narrowly skirting strollers and joggers - the irrepressible daredeviltry of youth. Behind them a shirtless, white-shorted Oriental man in glasses prods his vehicle forward with heavy, concentration and sweaty exertion.

Cyclists come in a variety of weights and colors and each seems to approach the sport with his or her definitive style.

Some people glance neither left nor right. For them, there is no scenery that is not straight ahead, or downward, in the gravel crunch under their bicycle's wheels. Others come au pair, romantic duos, for whom bicycling is merely an excuse for a tryst and concersation.

Then there are the hard-core cyclists, usually serious-eyed young men in twos and threes who bicycle not as a pastime to be mixed with love. They arrive wearing protective head gear, tight-fitting T-shirts and luminous shorts. They do not talk, but strap on odometers, buckle their feet into the pedals, and tool away on sleek, slim spindly-looking machines.

Nearby a jogger in acid green and lemon-striped running shoes arches and stretches, like a ballet dancer, before padding down the path. Somewhere in the shrubbery a mokeingbird competes with the steady susurrus from cars on the highway. The jogger has retreated into the distance, his run steady and complete.

At Great Falls Park in Virginia yesterday, though overcast, it was decidedly a day for the American living - and their effects: garbage cans overflowing with empty Kodar boxes, Heinz jars, Good Humor Chocolate Flavor-Coated Vanilla Ice Cream pop wrappers and even a dead car muffler; pretty girls trying to get picked up; ugly boys trying to pick up pretty girls; completed touchdown passes; just plain passes; a grandfather in from the south of France, grabbing little Johnny as he tries to peer over the falls and shouting. "No, No. Ca va?"; beer bottles wrapped in brown paper bags; a young woman hauling an ice chest full of beer, her own chest heaving under the C and S of a Coors T-shirt; a middle-aged man walking his very old mother, who is wearing a very worn pair of Keds; the smell of burning hot dogs mixing with the fading sweetness of the honeysuckle; lots of dogs.

Skip, walk, ski, walk, hop. Up the trail, sweat pouring from his receding, white-tufted hairline, a fat man huffs and puffs his way. His white T-shirt, soaked, clings to his body; his white boxer shorts, like a second skin, stick to the bulges and billows of his thighs. Skip, walk, skip, walk, hop. Minutes pass before he covers the ground that the previous jogger had run in seconds.

A gentle wind eases through the air. Somewhere, high above, it has pushed the clouds aside so the sun can drop down, breaking through the tree leaves, to scatter shadowy freckles onto the canal water.

Neophyte canoers zig zag back and forth across the water unsteady, but valiant, as a group of veterans slice through their wake and swiftly pass by. A plane roars above, louder, more insistent. And across ripples of the pea-soupy canal, something - not human - makes a jungle-like sound in an ailanthus stand.

Two cyclists, a father and his son, pause in the shade of a tree to let two mules and their tenders pass. The mules are towing the Canal Clipper, filled with Sunday sight-seers and the tinny, plinkity plink of a banjo.

The American holiday! A day to do what you want, how you want, when you want. But in families actions speak louder than words about the national experience.

A father and son are throwing a baseball. "Catch this way," the father exhorts, "with your thumb just lying on top of your mitt. You think the Yankees will ever sign you if your thumb is sticking up in the ear.?"

"I just want to have a catch daddy."

Under a nearby tree, a nubbybopper, maybe 11, in a green T-shirt, is holding a tiny plastic transistor radio shaped like a hamburger up to her ear. She's bouncing along to the music and her mother grabs it from her hand and says, "Stop that, it's disgusting."

Cyclists, in groups and singly, continue to trundle by. One scholarly looking young man, oblivious among the reset of the cyclists, pedals smoothly, smoking his pipe. A whiff of pot hangs in the air after he passes. A sun-tanned man in red shorts, his back and shoulder muscles undulating rhythmically, strides down the road.

With all the action on the road, there are even intrepid pedestrians. Two ladies, one in a straw hat, stroll along, deep in conversation. An elderly gentleman, his black suit coat tucked under his arm, comes along and stops under a mulberry tree. He begins to pick off the fruit and eat it.

A group of young people come along and ask him what he's eating, whether it's safe to eat.

In a European accent, he assures them that the fruit is perfectly safe.One of the young men springs off the ground like a basketball player into the tree to gather the fruit. He returns with his hands blackened with juice and barbecue. A dad is sweating over the mangled berries. He offers them to his girl friend. She declines. And they move on.

The gentleman continues to munch. "When I was in Trieste, as boy, the woman who did our laundry had one of those trees," he says to a young woman a lounging under a tree. "There the berries were long, like this," he spans his fingers to illustrate. "These are good, but not so good as those. Black and sweet. Umph," he closes his eyes in remembrance.

"Those people," he says, gesticulating at the retreating group. "They are a bunch of ignorant people. They don't know what's good for them and what isn't." He strolls down the pathway to another tree, stopping to sample the ripe fruit before the birds strip the trees.

Another dad is leading the family on a hike. "We'll get a little exercise and head over to the upper falls," he says.

"Dad," exclaims a 5-year-old son. "That's three miles from the ice-cream stand. That's way too far."

And then there is the ritual, relaxing hot coals and puts an inch-and-a-half thick steak on his son's paper plate.

The kid starts screaming. "WAHHHHHHHHHH. I want a hot dog.

"SHUT UP AND EAT YOUR STEAK," dad responds strongly. "It's good for you."

Two joggers, a man and a woman, labor up the pathway, ungraceful but determined, as pigeons whirl above them, effortlessly, disdainfully. For the birds, the park isn't just a weekend respite, they have all week to practice their dips and turns.