So many here and elsewhere have wonderful answers that I like so much better than the one I found. Unfortunately, the answer I hit upon manages to unlock more things than remain locked afterwards.
As you can tell, I'm struggling with this answer. I've not worked through all the implications, and my model of the world needs to be significantly readjusted given this new information. This has been a particularly weird year for me. Sister dead two days after finding out she was sick, check. Found 200+ mile diameter crater in Antarctica which ended the last Ice Age, check. Figured out age and purpose of the pyramids, check.
I'm really not sure I can take the rest of the year. We're barely half way through.
Edited 1 time(s). Last edit at 14-Jul-19 15:15 by GramPong.