A bloody mystery may just have been solved - but it took over 100 years.
A study was just published in the Journal of Glaciology.
It explains what's causing the blood red falls at the Taylor Glacier.
It turns out there's a large source of salty water that's turning the water blood red.
And this stuff may have been trapped for over a million years but the find led to another discovery that liquid water can exist inside a frozen glacier.
That's because salt water has to be colder than fresh water to freeze.
Taylor Glacier is now the coldest known glacier to have persistently flowing water.