NASA

The soil on the moon looks like it's wet, or is made of plaster or something. Look at how sharp the footprints and other impressions are?

Several powdered substances on earth exhibit this behavior. Anything finely powdered, such as cornstarch or flour, will clump when packed. Even earth dust, if sufficiently fine, will receive a print quite well even when dry.

The secret is in the microscopic structure of the individual soil particles, shown at right. On earth most soil particles rub against each other as they are acted upon by wind and water. This rubs off the rough edges. But lunar soil has no wind or water to erode it at the microscopic level, and so it retains those sharp edges that allow each particle to "catch" its neighbor and display the remarkable cohesion we can observe.

How could there be soil without erosive forces like wind and rain?

In Stanley Kubrik's 2001: A Space Odyssey the lunar mountains appear sharp and highly detailed. People were surprised to see more rounded features.

As a matter of fact, wind and water are not the only forces that cause erosion. The lunar soil is produced chiefly by the pulverization of the rocky surface by millions of years' worth of micrometeroids. And larger ones as well. When a large meteor strikes the lunar surface, a blanket of pulverized material called "ejecta" is thrown for miles around the crater.

The moon was also once seismically active. The "seas" are in fact ancient lava flows. The moon is tidally locked, which is a fancy way of saying that the same side always faces earth. The process of tidal locking exerts considerable forces on the lunar surface which can warp and distort features.

Harvard geologist Arthur Gold maintained the lunar soil would be several feet thick and that the Apollo astronauts would sink into it over their heads. Fortunately he was wrong about that, but the lunar soil is in fact several feet thick. But only the top inch or so is loose. The rest is very densely packed. But the top scientists at the time knew there would be particulate matter on the lunar surface, and they knew why.