#China is home to around 200 #tiankeng, which are mostly distributed from the central #Shaanxi province down to the #GuangxiZhuang autonomous region in the southwest. Roughly 1/3 of the country consists of #karst — the highest proportion of overall surface area of any country in the world — compared with just under 1/5 in the United States.
Picking back up on the GSA #cave#geology field trip. Day 2, cave 3.
This was after Mammoth cave, we went to nearby by Crystal Onyx cave. Unlike Mammoth this was a wet cave with lots of drippity dissolution and deposition #karst features.
Yes, it seemed to start out touristy-cheesy. But WOW! did it have a lot of neat geology going on!
We were the last tour of the day, just us geological nerds. So we hung out here waiting for our guide and the amazing discoveries below....
So 320-350 million year ago. Shallow sea. Brachiopods. Limestone. Then nearby mountain erode (as Pangea forms) and dump sands which turn into sandstone on top of the limestone layers. Much later uplift, but probably some magnesium rich fluids percolated through because we see these honeycomb features of dolomite!
Dolomite has a finer #karst dissection. It is more resistant so you get cool-o features like you see here.
My big #cave#geology thread. This was a trip examining a section of Coldwater Cave in Iowa as an Earth analog for #PlanetaryCaves. We were using this as an analog for #karst caves that might exist on Saturn's moon #Titan.
"Even the recent past eludes me. I can remember crying last week, for example, but not what the crying was about. I can remember around a memory, but rarely the memory itself. Nothing is medically wrong with me, at least not as far as I can tell. It has always been this way." For @longreads, Maddy Frank writes about memory, absence, and the karst of Missouri.
My colleague Helen Rutlidge (UNSW) has a new #preprint available for feedback and comments.
The title is "Negative Indian Ocean Dipole drives groundwater recharge in southeast Australia".
The #research identifies recharge events using observed changes in water level in bores (wells) and observations of water moving through adjacent #caves towards the water table.
These are compared to climate data from 2012 to 2021, all for the central west region of New South Wales, Australia. The data shows that the most significant recharge event during a decade of observations occurred during a particularly strong negative Indian Ocean Dipole period.
Through further analysis of recharge events dating back 1900, the authors show for the first time a significant link with negative Indian Ocean Dipole events.