There is always a new slant in women’s shoes. Sky-high stiletto heels and the tiptoe look gave way to relatively level, short-heeled pimps, walking shoes and flats. Heels reared up once again with the platform look, which is still riding high. But now the heel has actually dropped below the toes in a new kind of footwear: the odd-looking clodhoppers known to a growing band of sole sisters (and brothers) as Earth Shoes.

In some 40 shops across the country that specialize in Earth Shoes, more and more shoppers - including such celebrities as Mark Spitz, James Coburn, and Tony Curtis - are competing for limited supplies of clumpy footwear that defies most principles of shoemaking. Instead of sloping downward to the toe, the heel of the Earth Shoe is approximately one-half inch lower than the forward part. The rubber sole, in turn, gradually thickens in the direction of the toe, elevating the front of the foot and leaving the wearer balancing on his heels. “Its like walking barefoot on a soft, sandy beach,” says Raymond Jacobs, U.S. distributor of the footwear.

Jacobs has no problem boosting his product, despite its price (sandals, shoes, and boots well for between $23.50 and $42.50 per pair); buyers constantly tout the comfort of Earth Shoes. “They are about all we wear,” says Malibu Housewife Joan Lloyd. “my corkie platforms are now just taking up room in the closet.” Frank Palermo, 27, of Rye, N.Y., notes that his Earth Shoes did what four years at the Air Force Academy in Colorado could not do: teach him to stand up straight. The curious, heels-down construction forces the wearer to lean backward move, and thus to tuck in the belly and bottom and straighten the spine.

Some fanatic converts claim that Earth Shoes cure bunions and even stimulate blood circulation. Podiatrists have yet to weigh in with a verdict, but Earth Shoes seem far less dangerous than platforms, which has caused countless sprains and fractures. Most wearers admit, however, that the first few weeks can be uncomfortable. Earth Shoe rookies often complain of aching calves and thighs and a slowed-down gait.

Soft Terrain. Earth Shoes owe their appearance in the U.S. to Jacobs’ wife Eleanor, who first came across them in a small Copenhagen shop. “I tried them on and immediately my sore back felt better,” she says. That discovery led the Jacobses to track down the shoe’s designer, Anne Kalso, a yoga teacher who had for years observed the effects of shoes on posture. On a trip to South America she confirmed a favorite theory: lower heels mean better carriage. The Brazilian Indians, she decided, owed their erect stance to long years of sinking barefoot heels into soft terrain. Returning to Denmark, she perfected a primitive version of today’s shoe and tested it herself on 500-mile hikes.

After talking Kalso into granting him U.S. distribution rights, Jacobs opened the Manhattan shop in 1970. Later he opened four more and awarded dealerships to 35 other owners, 20 of them in the past year. “It’s not just a business, it’s a life-style,” explains Eleanor Jacobs. “Most of our shop owners, as well as customers, are into things like yoga and vegetarian eating.” They are also totally into their strange footwear. “When I got married last weekend,” confesses Albie Sikirdji, a Bronx student, “I wore my Earth Shoes.