I have a mental picture of a dramatic day on Earth when a less than moon sized body struck the pacific area in a trajectory slightly east to west and up from the equator. BAM the collision sent more material up into orbit that the impact body. The heavier elements in the Earth came up as the molten crater filled in.

The ejecta made a bright fiery ring around the earth and settled down to several spherical bodies and finally into one called the moon. One side of the moon had heavier elements than the other which was subjected to less gravity. Only one size faces earth.

Back on Earth the heavier gold was sloshed up around the east side of the ring of fire. Some in shocked quartz and some all the way to the surface. The ring of fire may be a remnant of the smaller impact object. We have found the moon to be mostly light weight Earth stuff.

How long ago could this have happened? I dunno.

PS it also may have given the earth its seasonable wobble.