So, long #geology story long, I was driving the Modesto-Oakland leg of my weekend journey on Friday, and I accidentally went up Corral Hollow Rd instead of Patterson Pass. It was an interesting explore, although ultimately it dead-ended and I had to turn around. There’s a state park in there called Carnegie (really a rec vehicle place), so I checked out the butterfly situation. I crossed a wash several times, and I saw a lot of this material. At first I assumed it was old road tar, but it was weathering funny. I picked up a piece and discovered it was quite heavy, so I snagged a chunk and brought it home to clean. Seems to have a lot of feldspar - probably calcic. And mostly fine-grained mafics.
My guess is that I stumbled upon some un-serpentinized ultra-basic material from the Franciscan. I’ve heard it’s around, but in all my years of living in Northern #california I’ve never seen any in the field.
Anybody else know?
Now that the specimen is clean and dry, my loupe shows growth or reaction rings on the edges of the feldspars, and apparently some small garnets. So I'm going with Gabbro or possibly Eclogite.
The crystallization of large replenished magma bodies is amazingly complex. The photos of layered rocks from the Bushveld Complex in this new #OpenAccess paper are mind-bogglingly wonderful 🤩 🤯 🤓 . The wider applicability of their conclusions might be disputed by some, but good stuff though! https://doi.org/10.1016/j.lithos.2024.107621#Geology#Igneous#LayeredIntrusions
#Eruption#Volcanos#Geology
Per the Guardian, the erupting volcano,
"Ibu is one of Indonesia’s most active volcanoes, erupting more than 21,000 times last year. "
Doesn't that translate to it erupted all year long? How are we defining an eruption if we can count multiple eruptions a day?
#OnThisDay, May 18, 1980, Mount St. Helens erupted in Washington state. It has often been declared the most disastrous volcanic eruption in U.S. history (depicted in St. Helens, 1981)
Happy birthday to Danish #seismologist Inge Lehmann (1888 – 1993) who demonstrated that the Earth's core is not a single molten sphere, but contained an inner solid core, in ‘36. She was a pioneer #womanInScience, a brilliant seismologist & lived to be 105.
As she first postulated, the #earth has roughly 3 equal concentric sections: mantle, liquid outer core & solid inner core. 🧵1/n
Opals form in cavities within rocks. If a cavity has formed because a shell was buried in sand or clay that later became rock, and conditions are right for opal formation, then it forms a fossil replica of the original object.
From a 1929 book on Child's Geography:
"But the World still kept on cooling and cooling, and as it cooled it shrank and shriveled and wrinkled and crinkled and puckered like the outside of a prune. You know a prune was once smooth and round when it was a plum. These little wrinkles and crinkles rose up out of the ocean and were the continents and mountains, so you see how big the wrinkles and crinkles really are."
TIL that not only is the Grand Canyon not the deepest canyon on land in the world, it’s not even the deepest one in the USA (where it’s third deepest!)
The deepest land canyon is in the Himalaya Mountains.
@bodiednovel I've studied astrophysics and have a strong interest in geology. I might not know the answers to your questions, but I'm happy for you to ping me to take a look.
