Odd time markers

What do you call a landmark in time? Like September 11th, or like your elderly relatives telling time by when children were born?

I'm going through landmarks in time lately. "Finished off the remaining perishables Krissy and the kids left behind" was a bit back now, while "doing the last laundry from them" is happening right now. I'll be doing some cleaning out the freezer (eating and cooking stuff) over time -- that will take longer.

When I'm not here, I'm on Twitter. I really appreciate the room to ruminate a bit. 140 characters is nothing at all.

And you can all scroll past me reasonably quickly either way.