bprd: abyss of time

So! The other day I mentioned an Artifact of Ancientness!


That triangle is a moon rock. It is a piece of basalt three point something billion years old, most of the age of the Earth and a not-too-shabby fraction of the age of the universe.

The rock it’s pointing at is older.


The Archaean Eon is named for an old word meaning “ancient.” The Acasta Gneiss is one of the few rock formations from the eon before that. When the Earth was cooling off enough that the floor was now only partially made of lava, that’s when the gneiss was formed. Yup: that rock predates plate tectonics.

As it happens, there’s a four-ton boulder from the Acasta Gneiss on display at the Museum of the American Indian. It pretty much just looks like a rock. Since this is D.C., and the museums here are pretty OK, there’s another piece next door at the natural history museum. This one has been sliced open and polished and looks like it could plausibly be from the same source as the stone in the pendant.

So. Four billion years. The oldest known Earth rock. Older than every living thing, every fossil, and all except maybe the oldest continents. It’s fortunate that rocks don’t need to breathe, because otherwise this one would suffocate in all this newfangled “oxygen.” There are stars younger than this rock that I wear around my neck.

Have I mentioned that I think this is really cool?