Garbage doesn't lie. The evidence of junk-food wrappers, liquor bottles and girlie magazines often flies in the face of what we tell ourselves -- and what we tell others -- about what we do. By comparing the results of surveys of food consumption with the contents of the respondents' trash containers, the garbage project discovered a phenomenon they called the Lean Cuisine syndrome -- people consistently underreport the quantity of junk food they eat, and overreport the amount of fruit and diet soda they consume. Most people also underreport their consumption of alcohol by 40 to 60 percent; on the other hand, heads of households regularly exaggerate the amount of food their families consume -- the Good Provider syndrome. "What people claim in interviews to have bought and consumed, to have eaten and drunk, to have recycled and thrown away," the authors write, "almost never corresponds directly or even very closely to the actual remnants of material culture in their Glad or Hefty bags."

If we are deluded about our own patterns of consumption, it follows that we might also hold mistaken notions about garbage in general. Most people believe, for example, that expanded polystyrene foam -- which is used in fast-food packaging, coffee cups, packing "peanuts" and the molded forms that come around stereo equipment -- constitutes a major proportion of our garbage and represents a serious strain on the capacity of landfills. But the garbage project found that expanded polystyrene foam accounted for less than one percent of the volume of garbage dumped in landfills between 1980 and 1989. And what about the 16 billion disposable diapers that Americans use every year? They constituted an average of no more than 1.4 percent, by volume, of the average landfill's total solid-waste contents during 1980-89.

What, then, makes up the biggest portion of garbage? Not surprisingly -- in an information age -- it is paper, which takes up over 40 percent of the contents of landfills by volume. (The two runners-up are construction debris and yard waste, which consists of grass clippings and leaves.) Newspapers alone constitute about a third of the volume of discarded paper; a year's worth of The New York Times takes up about 1.5 cubic yards, as much space as 18,660 crushed aluminum cans or 14,969 crushed Big Mac clamshells would require.

But, surely, paper is biodegradable? Well, yes and no. The garbage project regularly uses newspapers to date garbage layers precisely because, even after several decades, they remain intact and perfectly legible. The problem, the authors say, is that, landfills "are not vast composters; rather, they are vast mummifiers." There is biodegradation, but its pace is measured in centuries, not decades. Even organic materials, such as food scraps, remain unchanged after 30 or 40 years. Mr. Rathje and Mr. Murphy cite an account of an excavation of an ancient Roman garbage dump in which the smell of putrefaction remained unbearable even after 2,000 years.

As the authors point out, there has always been garbage, and almost always a lot of it. They quote an estimate that the street level of the ancient city of Troy rose almost five feet per century as a result of debris accumulation. Present-day street levels on the island of Manhattan are typically 6 to 15 feet higher than they were in the 17th century; it wasn't until 1895 that the city undertook systematic garbage removal.