"If it had been lying on the surface, yes. But this came from the bottom of a shaft over seven hundred feet deep! In other words, it was on the surface for all that time—then suddenly it's seven hundred feet down." Steinfield gestured toward the wall chart again. "As I said, we find the same thing all over Farside. We can estimate how far down the old surface used to be. Below it we find old rocks and structures that go way back, just like on Nearside; above it everything's a mess—the rock all got pounded up and lots of melting took place when the garbage came down, all the way up to what's now the surface. It's what you'd expect."

Hunt nodded his agreement. The energy released by that amount of mass being stopped dead in its tracks would have been phenomenal.

"And nobody knows where it came from?" he asked.

Steinfield repeated his head-shaking act. "Some people say that a big meteorite shower must have got in the way of the Moon. That may be true—it's never been argued conclusively one way or the other. The composition of the garbage isn't really like a lot of meteorites, though—it's closer to the Moon itself. It's as if they were made out of the same stuff—that's why it looks the same from higher up. You have to look at the microstructure to see the things I've been talking about."

Hunt examined the specimen curiously for a while in silence. At length he laid it carefully on the top of one of the benches. Steinfield picked it up and returned it to its drawer.

"Okay," Hunt said as Steinfield rejoined him. "Now, what about the Farside surface?"

"Kronski and company."

"Yes—as we discussed yesterday."

"The Farside surface craters were made by the tail end of the garbage-dumping process, unlike the Nearside craters, which came from meteorite impacts, oh . . . a few billion years back. In rock samples from around the rims of Farside craters we find that things like the activity levels of long half-life elements are very low—for instance, aluminum twenty-six and chlorine thirty-six; also the rates of absorption of hydrogen, helium, and inert gases from the Solar wind. Things like that tell us that those rocks haven't been lying there very long; and since they got where they were by being thrown out of the craters, the craters haven't been there very long, either." Steinfield made an exaggerated empty-handed gesture. "The rest you know. People like Kronski have done all the figuring and put them at around fifty thousand years old—yesterday!" He waited for a few seconds. "There must be a Lunarian connection somewhere. The number sounds like too much of a coincidence to me."