Forget haunted houses. This glacier bleeds.

It's October, which means fake blood is everywhere: dripping down haunted house walls, smeared on zombie costumes, oozing out of novelty cupcakes. But what if I told you to forget haunted houses because there's a place on Earth where blood really does pour out of the ice?

Close your eyes for a second. It's 1911. You're part of a British expedition to Antarctica, trudging across a frozen valley with nothing but white ice in every direction for miles. Then someone stops and points. At the foot of a glacier, a crimson stain is spilling down the ice like an open wound.

The captain's mate and two others are instructed to leave camp and make their way near it. They need a sample of the fluid to take back with them. The mate is apprehensive, but must be brave. After all, the men are split right down the middle. Half insist there must be a scientific explanation. The other half are making the sign of the cross and swearing it's a bad omen.

The mate spots a battered tin wedged between the rocks. Inside is a brittle, water-stained page, written more than a century earlier:

"The 14th day of February. Sky clear, wind bitter from the south. This morning, the man breaking trail ahead cried out, and every one of us hurried up the valley to see it: from the foot of the great ice wall, a stain of crimson running down as fresh as from a cut throat. The men will not stop crossing themselves. I write it down here plainly, that whoever reads this may know I did not dream it."

Someone had seen it before them. The place is real. It's called Blood Falls, and it spills out of the Taylor Glacier in Antarctica. So what is it?

Here's what's really happening.

Researchers drilling deep into the glacier made a startling discovery: the frozen remains of an entire pack of enormous prehistoric creatures, trapped together in the ice for millions of years. For most of that time, their blood stayed frozen solid. But as Antarctica has warmed, the ice around them has begun to thaw, and their preserved blood is now seeping out through cracks in the glacier.

Are you kidding? That's unbelievable!

You're right. Don't believe it, because there is no pack of beasts, and there was no old note, either. No one in the 1700s ever saw Blood Falls; nobody had even sighted Antarctica until around 1820. The 1911 expedition was real, though. They actually did see it, and its geologist, Griffith Taylor, guessed the red came from algae. He was wrong too.

The real reason is this: deep beneath the glacier lies an ancient reservoir of extremely salty, iron-rich water that has been sealed away for possibly more than a million years. When the iron-rich brine emerges and is exposed at the surface, oxidation helps produce that extraordinary blood-red color. And no, it isn't caused by warming. It's pushed out by the crushing weight of the glacier above.

And here's the twist worthy of Halloween: that ancient water is alive.

Microbes live inside it with no sunlight and almost no oxygen, surviving by "breathing" iron and sulfur. Scientists study them to imagine what life might look like beneath the ice of Jupiter's moon Europa, or under the surface of Mars. And creatures like these have surprised us before: a bacterium from a Yellowstone hot spring gave us the enzyme behind PCR testing.

So I'll leave you with this for Halloween:

What if fear is sometimes just the name we give something before we understand it?

Have you ever done that? I have.

That question lies at the heart of Roots of Fear, Book Two of the Privileged Secrets trilogy.

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