HOT ROCKS…EASTERN SIERRA VOLCANIC FORMATIONS
Although we visited Mono Lake only two weeks ago, it feels like we have traveled months since then; maybe the ripeness of our unshowered bodies adds to this sensation! We saved this photo courtesy of USFS, as the Crater and Cone is massive enough we couldn’t get a good picture at ground level.
This cone and other named the Mono Craters make up the youngest mountain range in North America, with evidence of activity only 600 years ago. A 1.25mile crater from the 1st eruption was later altered by a lava dome inside the crater when magma pushed to the surface during the 2nd eruption. There are also towers 20-50 feet high from magma seeping through the cracks.
Devil’s Postpile! The basalt erupted 80,000 years ago, cooling from top to bottom, forming 6 sided columns with a flat top, that is shiny from glacial polish. It was like walking on a beautifully laid mosaic floor on top.
760,000 years ago, an eruption blew 150 cubic miles of magma during a brief 6 day period. The massive crater collapsed and partially filled to form a 9 mile x mile depression. The map above gives you a sense of the huge area that was affected. Bishop Tuff was formed from the erupted material when the Long Caldera blew. It is made of volcanic rocks trapped within fine-grained ash, welding it together as it cooled.
COOL ROCKS…THE OLDEST IN THE SIERRAS
Convict Lake is made up of Sedimentary Rock, formed 500 Million years ago! Extreme heat and pressure, a process called metamorphism, along with uplift, faulting and erosion further this area. It is mind expanding to contemplate 500 Million years, and all the conditions and processes involved in the product we see today. How brief and inconsequential a human life feels. I am so grateful to the impact of Science in our lives, that provides us with facts and information, allowing us to contemplate existence so far beyond what we live in our daily lives. Now, the story behind the name; it was named Convict Lake when 3 prisoners from jail in Carson City, NV escaped to this area. After killing a local who happened on them, a citizen posse tracked them to this lake and took them into custody. The two adult prisoners were hung, and the 17 year old was returned to a different, perhaps more secure facility?