I grew up going to the High Sierras every summer with my family. They are my home mountains.
It wasn’t until I took a geology class at Carnegie Mellon that I started to be able to think about my mountains’ history, their composition. Geology is the demography of the earth, it’s a way of understanding what’s here, how it got here, and what it might do in the future.
My favorite kind of rock is the kind that is most common in my mountains: igneous rock, that which came from inside the earth but hasn’t been here long enough to get turned to dirt and then become rock again at the bottom of the ocean (that’s sedimentary rock).
Some mountains only let you see one kind of igneous rock. Some have just intrusive igneous, molten rock that got close but didn’t reach the open air and then cooled. They tend to be speckly, like a robin’s egg.
Some have just extrusive, where lava flowed on the surface of the earth and formed rocks that sometimes have little air bubbles in them.
Other places have cooled volcanic mud, which is much looser, full of little and big bits of stone and hard-ish earth. It just falls apart under the onslaught of rain; it’s the weakest form of igneous rock, but breaks beautifully.
Here’s a video I took of a place that lets you see all 3, right on top of each other in Gargoyles in the Western Sierra Nevada mountains:
Gargoyles is a beautiful place, with striking contrasts between the wide-open valley and the jagged, crumbling cliffs. It’s also a place where the stones tell a story of times when it wasn’t so peaceful, when the ground heaved under rising igneous rock and boiled over with volcanic mud and lava. There’s something peaceful about seeing evidence of all of that turmoil and realizing it all ended up beautiful anyway.
“And the people in the streets below Were dancing round and round And guns and swords and uniforms Were scattered on the ground”–Paul Simon