Out to the east as the loop straightens out, that chain of pale, symmetrical domes marching north is the Mono Craters — and they are, by most reckonings, the youngest mountain range in North America. The most recent of those domes erupted only about six hundred and fifty years ago. In geological time, that is this morning. This basin is not finished being built.
They're made of obsidian and pumice — volcanic glass. The Kutzadika'a people of this basin, and tribes trading with them, worked that glass into tools and points that traveled all over the Sierra; you are looking at a stone-age factory district.
And here's the connection to the story you heard at Grant Lake: when Los Angeles needed to get Rush Creek's water OUT of this closed basin — because Mono Basin has no natural outlet — its engineers bored a tunnel eleven miles long right under this volcanic ground, through the roots of these craters, to reach the Owens River drainage. Water that fell on the peaks behind you used to end its journey in Mono Lake; the tunnel under those buttes is where it was made to change its mind.
Ahead a few minutes is the north junction with Three Ninety-Five. If you have any daylight left, Mono Lake itself — with its limestone towers standing in the water — is ten minutes north, and it is one of the strangest and most beautiful places in California.
Photo: NASA · Public domain