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I wonder why lakes aren't salty? It's clear why rivers and lakes that eventually empty into the ocean are fresh. Rainwater washes the salt downstream to its ul

by ccleve 9y ago

I wonder why lakes aren't salty? It's clear why rivers and lakes that eventually empty into the ocean are fresh. Rainwater washes the salt downstream to its ultimate destination. But many lakes do not have an outlet that leads to the sea. Water flows in and evaporates. Where does the salt go in that case? Or is it possible that the article doesn't tell the full story, and that salty rocks are confined to a limited number of areas?

Retric 9y ago
Most lakes have an outlet. The US great lakes for example all share a river that's also the source of Niagara Falls. On top of that, some lakes do get salty. Such as the 'salt lake' near Salt Lake City.
- lobster_johnson 9y ago
  ...which is named the Great Salt Lake, by the way.
nordsieck 9y ago
> Normally, water that has accrued in a drainage basin eventually flows out through rivers or streams on the Earth's surface or by underground diffusion through permeable rock, ultimately ending up in the oceans. However, in an endorheic basin, rain (or other precipitation) that falls within it does not flow out but may only leave the drainage system by evaporation and seepage. The bottom of such a basin is typically occupied by a salt lake or salt pan. https://en.wikipedia.org/wiki/Endorheic_basin https://en.wikipedia.org/wiki/Endorheic_basin It turns out that they are salty. They are often not as salty as the ocean though because oceans have been getting saltier for millions of years.
ajross 9y ago
Time scale. Lakes are static bodies of water for a few thousand to a million years at a time before some flood or glacier or whatnot flushes them out to the ocean. The ocean stores the accumulated salts of 4.7 billion years of surface rocks.
- javajosh 9y ago
  "Time scale" is actually a wonderful, pithy, accurate explanation for a lot of things!
- coolso 9y ago
  > The ocean stores the accumulated salts of 4.7 billion years of surface rocks. I've always wondered. Were the rocks really there for 4.7 billion years, or did God create the rocks in such a way to trick scientists into believing they've been there for 4.7 billion years?
  - djsumdog 9y ago
    Sarcasm like this doesn't typically go well here. This isn't Slashdot or /r/atheism. Believe it or not, there are religious people of various faiths on here, both in and out of the tech community. Statements like this don't add to the discussion, are frivolous and sorta mock peoples' believes.
    - coolso 9y ago
      I wasn't being sarcastic, or mocking anyone's beliefs, scientific or religious. Nor am I an atheist or got lost and think I'm on Slashdot. I was merely putting forth a question I've always thought was intellectually interesting, something that's supposed to be encouraged here. [1] [1] https://news.ycombinator.com/newsfaq.html https://news.ycombinator.com/newsfaq.html
      - Sylos 9y ago
        In that case, the answer to your question is that there is no answer, that there can never be an answer (unless God tells us) and that there does not need to be an answer. If God really made it so that it's impossible to tell that they are not 4.7 billion years old, then it is simply impossible to tell so, hence there can be no answer. And there does not need to be an answer, because if there really is no way to tell that they are not 4.7 billion years old, then by definition there cannot be any situation where it would make a difference. So, it's perfectly valid to just state that they are 4.7 billion years old. I am in fact atheist, this is the viewpoint that I have from the discussion whether maybe our entire universe is just a computer simulation ran by some alien race or such. If we talk about it with the religious tangent, there's of course further questions: Some people interpret the Bible to contain an age of the universe. So, is that interpretation of the Bible wrong or not? And if it's not, why would God want to trick us with those rocks? Did he create the universe some few thousand years ago, but thought it'd be a more interesting world, if there was some backstory to it? So, does he want us to explore this backstory? Or is it a test of your faith in the Bible? ...which to my knowledge really doesn't state a concrete date for creation, so at least to me that'd be strange.
cperciva 9y ago
Some lakes are salty. The Dead Sea and the Caspian, for example. But many lakes do not have an outlet that leads to the sea. Water flows in and evaporates. Where does the salt go in that case? It sticks around. The terminal lakes which aren't salty are generally ones which only formed recently (e.g., after the most recent glaciation) or ones which are not fed by rivers (e.g., Oregon's Crater Lake).
- ajross 9y ago
  FWIW, the Dead and Caspian seas are actually dismembered bits of ocean. They're salty because their water was originally salty. The only salty lake I can think of that didn't begin with ocean water is the Great Salt Lake, which is an evaporated basin from a much larger lake that just happened to sit on salty bedrock.
  - eesmith 9y ago
    https://en.wikipedia.org/wiki/Salt_lake https://en.wikipedia.org/wiki/Salt_lake lists a number of salt lakes. One is https://en.wikipedia.org/wiki/Mono_Lake https://en.wikipedia.org/wiki/Mono_Lake , which did not begin with ocean water. Another one is https://en.wikipedia.org/wiki/Don_Juan_Pond https://en.wikipedia.org/wiki/Don_Juan_Pond , which is a shallow Antarctic hypersaline lake that almost never freezes. https://en.wikipedia.org/wiki/Little_Manitou_Lake_(Saskatchewan) https://en.wikipedia.org/wiki/Little_Manitou_Lake_(Saskatche... is a terminal lake which formed after the Ice Age. I'll also add a non-endorheic salt lake, https://en.wikipedia.org/wiki/Great_Salt_Plains_State_Park https://en.wikipedia.org/wiki/Great_Salt_Plains_State_Park , made salty from the dried salts from an ancient inland sea. (I think it's the Western Interior Seaway, but I could be wrong.) In any case, it began with ocean water, which dried up, and that salt is dissolving again.
BurningFrog 9y ago
Most lakes actually do have an outlet to the sea. Because they normally fill up whatever basin they're in and pour over some edge.
deleted 9y ago
[deleted]
gumby 9y ago
The situation you describe is rare, so you don’t see it often. But the Dead Sea, and Great Salt Lake are examples of what you describe. Plus, as another commenter says, it takes time and lakes are typically transient structures on a geological timescale.

by ccleve 9y ago

Retric 9y ago

Most lakes have an outlet. The US great lakes for example all share a river that's also the source of Niagara Falls. On top of that, some lakes do get salty. Such as the 'salt lake' near Salt Lake City.

lobster_johnson 9y ago
...which is named the Great Salt Lake, by the way.

nordsieck 9y ago

> Normally, water that has accrued in a drainage basin eventually flows out through rivers or streams on the Earth's surface or by underground diffusion through permeable rock, ultimately ending up in the oceans. However, in an endorheic basin, rain (or other precipitation) that falls within it does not flow out but may only leave the drainage system by evaporation and seepage. The bottom of such a basin is typically occupied by a salt lake or salt pan. https://en.wikipedia.org/wiki/Endorheic_basin https://en.wikipedia.org/wiki/Endorheic_basin It turns out that they are salty. They are often not as salty as the ocean though because oceans have been getting saltier for millions of years.

ajross 9y ago

Time scale. Lakes are static bodies of water for a few thousand to a million years at a time before some flood or glacier or whatnot flushes them out to the ocean. The ocean stores the accumulated salts of 4.7 billion years of surface rocks.

javajosh 9y ago
"Time scale" is actually a wonderful, pithy, accurate explanation for a lot of things!
coolso 9y ago
> The ocean stores the accumulated salts of 4.7 billion years of surface rocks. I've always wondered. Were the rocks really there for 4.7 billion years, or did God create the rocks in such a way to trick scientists into believing they've been there for 4.7 billion years?
- djsumdog 9y ago
  Sarcasm like this doesn't typically go well here. This isn't Slashdot or /r/atheism. Believe it or not, there are religious people of various faiths on here, both in and out of the tech community. Statements like this don't add to the discussion, are frivolous and sorta mock peoples' believes.
  - coolso 9y ago
    I wasn't being sarcastic, or mocking anyone's beliefs, scientific or religious. Nor am I an atheist or got lost and think I'm on Slashdot. I was merely putting forth a question I've always thought was intellectually interesting, something that's supposed to be encouraged here. [1] [1] https://news.ycombinator.com/newsfaq.html https://news.ycombinator.com/newsfaq.html
    - Sylos 9y ago
      In that case, the answer to your question is that there is no answer, that there can never be an answer (unless God tells us) and that there does not need to be an answer. If God really made it so that it's impossible to tell that they are not 4.7 billion years old, then it is simply impossible to tell so, hence there can be no answer. And there does not need to be an answer, because if there really is no way to tell that they are not 4.7 billion years old, then by definition there cannot be any situation where it would make a difference. So, it's perfectly valid to just state that they are 4.7 billion years old. I am in fact atheist, this is the viewpoint that I have from the discussion whether maybe our entire universe is just a computer simulation ran by some alien race or such. If we talk about it with the religious tangent, there's of course further questions: Some people interpret the Bible to contain an age of the universe. So, is that interpretation of the Bible wrong or not? And if it's not, why would God want to trick us with those rocks? Did he create the universe some few thousand years ago, but thought it'd be a more interesting world, if there was some backstory to it? So, does he want us to explore this backstory? Or is it a test of your faith in the Bible? ...which to my knowledge really doesn't state a concrete date for creation, so at least to me that'd be strange.

cperciva 9y ago

Some lakes are salty. The Dead Sea and the Caspian, for example. But many lakes do not have an outlet that leads to the sea. Water flows in and evaporates. Where does the salt go in that case? It sticks around. The terminal lakes which aren't salty are generally ones which only formed recently (e.g., after the most recent glaciation) or ones which are not fed by rivers (e.g., Oregon's Crater Lake).

ajross 9y ago
FWIW, the Dead and Caspian seas are actually dismembered bits of ocean. They're salty because their water was originally salty. The only salty lake I can think of that didn't begin with ocean water is the Great Salt Lake, which is an evaporated basin from a much larger lake that just happened to sit on salty bedrock.
- eesmith 9y ago
  https://en.wikipedia.org/wiki/Salt_lake https://en.wikipedia.org/wiki/Salt_lake lists a number of salt lakes. One is https://en.wikipedia.org/wiki/Mono_Lake https://en.wikipedia.org/wiki/Mono_Lake , which did not begin with ocean water. Another one is https://en.wikipedia.org/wiki/Don_Juan_Pond https://en.wikipedia.org/wiki/Don_Juan_Pond , which is a shallow Antarctic hypersaline lake that almost never freezes. https://en.wikipedia.org/wiki/Little_Manitou_Lake_(Saskatchewan) https://en.wikipedia.org/wiki/Little_Manitou_Lake_(Saskatche... is a terminal lake which formed after the Ice Age. I'll also add a non-endorheic salt lake, https://en.wikipedia.org/wiki/Great_Salt_Plains_State_Park https://en.wikipedia.org/wiki/Great_Salt_Plains_State_Park , made salty from the dried salts from an ancient inland sea. (I think it's the Western Interior Seaway, but I could be wrong.) In any case, it began with ocean water, which dried up, and that salt is dissolving again.

BurningFrog 9y ago

Most lakes actually do have an outlet to the sea. Because they normally fill up whatever basin they're in and pour over some edge.

deleted 9y ago

[deleted]

gumby 9y ago

The situation you describe is rare, so you don’t see it often. But the Dead Sea, and Great Salt Lake are examples of what you describe. Plus, as another commenter says, it takes time and lakes are typically transient structures on a geological timescale.