HOW does a New Jersey town at the edge of commuting distance to New York, with its own interchange off Interstate 78, not only stay largely rural but even keep a flavor of the 18th century? In Tewksbury Township, two factors explain this feat: zoning and geology.

The geology, of course, came first. A fault line slices through Tewksbury Township, separating rolling hills at the southern end from abruptly steeper ones toward the north. Ted Koven, the founder of the Tewksbury Land Trust, called the line ''very distinctive.'' This natural boundary and the rough terrain north of it were important in saving the township from excessive development. More recently, when living on a dirt road at the top of a hill began to be fashionable, the town government took over, restricting development and preserving open space.

Today, the township still includes miles of bucolic farmland and forest, and its several tiny hamlets, dating back to the 1700's, are connected by narrow, often twisting roads. On some of them, a driver may meet a rider on horseback nearly as often as another car. It's a contrast to city life that appeals to many weekenders from the city; about 15 percent of the township's houses are now second homes.

Dan and Robin Mathews live during the week in an apartment building on the East Side of Manhattan, near the frenzied traffic of the 59th Street Bridge. On weekends, they look out at their four partially wooded acres and listen to a rushing creek from their 19th-century farmhouse. They bought it when the elder of their sons -- now a freshman in college -- was an infant. ''We wanted a wooded, hilly area where we could go year-round,'' said Dan Mathews, a lawyer. ''We wanted a home that was private and had vistas without looking onto the neighbors.''

Robin Mathews, a psychotherapist, added: ''We wanted the opposite of the city. Our neighbors kept animals, and our kids were transfixed. In the springtime, they would visit the lambs and chicks every weekend and see them get bigger and bigger.''

Over the years, the Mathewses have spent their time renovating the house, scouting antique furniture from nearby shops, and using their stream for splashing in summer and skating in the coldest winters.

Yet Tewksbury is 20 minutes from everything a weekender might need -- restaurants, supermarkets, antiques shops, movie theaters and two enormous shopping malls (Bridgewater Commons and Short Hills).

The Scene

Once, loggers worked in the rugged hills to the north; one area where the terrain abruptly steepens is called the Dinner Pot, because wives left pots of dinner there for their husbands' break from wood-cutting. Settlement is still thin in the higher hills. In the gentler country to the south, horse farms line Hill and Dale Road. There is also the occasional cul-de-sac with modern houses, and a cluster of town houses is under development just off I-78.

The town's preservationist attitude -- and its relative powerlessness against Hunterdon County officials with other needs in mind -- is embodied in the skirmishes with the county over the town's small stone arch and metal truss bridges. Tewksbury's residents, preferring to keep traffic slow, want to keep the bridges narrow, but ''if one needs repair,'' said Shaun Van Doren, president of the Tewksbury Historical Society, ''the county widens it.'' Residents are currently fighting a county plan to widen one 16-foot bridge to 26 feet.

Another force for preservation is the town's Scenic Roads Commission, which oversees 33 designated roads, encouraging homeowners to follow guidelines on paving, lighting and the like so properties blend with the landscape, said Lisa Stryker, the group's chairwoman.

Tewksbury's largest settlement, Oldwick, was founded in 1734. In its center are the steepled Zion Evangelical Lutheran Church, the Tewksbury General Store and the Tewksbury Inn, a restaurant. Most of Oldwick's houses are Victorians and colonials with paned windows, front-yard wells and spacious porches, dating primarily from the 19th century.

Northwest of Oldwick is Mountainville, at the confluence of several streams. It is little more than an intersection with an antiques store and a general store that has a hitching post out back for horses.


Tewksbury's splendid countryside contains plenty of recreational land. The largest park is the 195-acre Christie Hoffman Farm, where the town sponsors many activities and hunting is permitted on scheduled days. Hikers and bird-watchers enjoy the Whittemore Nature Preserve and the Cold Spring Preserve. Most heavily wooded is the 50-acre Christmas Tree Farm, where a generation of residents has picked out its holiday trees. All of the parks are open for recreation, including hiking, picnicking and horseback riding, but closed to trail bikes, motorized vehicles and unleashed dogs.

On weekends, when traffic is light, bicyclists take to the town roads. So do people on horseback, though they are more likely to be on the 100 miles of riding trails maintained by the Tewskbury Trail Association, a private group. Membership is open to Tewksbury residents and to nonresidents who board horses in the township. The annual fee is $50 for families, $40 for individuals and $20 for nonriders.