5 ms·
> He realised the water at the surface of the lake was drinkable Can someone explain this phenomena? How can the water in a sea-cave become potable?
by biggc 9y ago
> He realised the water at the surface of the lake was drinkable
Can someone explain this phenomena? How can the water in a sea-cave become potable?
- Markoff 9y agopretty sure it was inland cave, so not sure why the water should not be drinkable and how is it surprising they mention the caves where flooded 60000 years ago, which is long time ago to replace all the original sea water with fresh water from other sources or maybe it's condensated water from walls of cave creating layer on top, though not sure how would that work
- NegativeLatency 9y agoFresh water is less dense than salt water, so perhaps fresh water seeped through rocks from above and didn't mix with the sea water.
- titanomachy 9y agoI'm not familiar with Mallorca's hydrogeology, but I've done some cenote (cavern) diving in Mexico's Yucatan peninsula. The caves are inland, but sea water infiltrates through the porous and channel-filled rock. The water nearer the surface is rainwater. The narrow region where freshwater and seawater intermingle is called the halocline, it creates a cool optical distortion which reminds me of the "oil paint" filter in photoshop.
- stingraycharles 9y agoThis probably is a stupid question, but wouldn't the salty seawater be lighter than the rain water, and thus be at the surface ?
- cr1895 9y agoSalty water is quite literally more dense than fresh water. Average seawater is 1025 kg/m^3, pure water is nominally 1000 kg/m^3. Somewhat related video: dense brine that doesn't freeze in Arctic sea ice sinks rapidly through liquid seawater below https://youtu.be/WyWn1XJ9kTE https://youtu.be/WyWn1XJ9kTE
- stingraycharles 9y agoOh geez, you're absolutely right, I don't know what I was thinking. I probably needed my morning coffee.
- x2398dh1 9y agoIt's OK, stingrays like you aren't expected to know about polar regions and super cold water.
- logfromblammo 9y agoWater can stratify if the layers have different temperature, salinity, or change in density from other causes. https://en.wikipedia.org/wiki/Halocline https://en.wikipedia.org/wiki/Halocline If there is no convection or wave-action to mix the saltwater with the fresh, they can coexist in the same vessel, with very slow diffusion of salt into the fresh layer. If the fresh layer is refreshed by rainfall or fresh outflows of groundwater, the top may always be drinkable, even as the bottom is not.