If rock formed under lower gravity circumstances, would that necessarily determine a lower density? And if so, and something happened to increase gravity, would that slowly increase the density of materials either excavated or unexcavated? I could see a lower density from volcanic rock cooling under lower gravity, but I don't see how increased gravity after the fact could increase the density post volcanic formation and cooling. Seems that post cooling the density would be set. Just curious in case I'm missing something.