For a long time I’ve taught about the Kola Superdeep Borehole, the farthest humans have dug into the Earth’s crust. While getting 12,262 m deep, it never broke through to the mantle.
Now, scientists have gotten core samples from the mantle, without having to beat the Kola borehole. By digging along the Mid Atlantic Ridge, they were able to pull rocks from the upper mantle from a “tectonic window” where the mantle is very near the surface (of the Earth, not the ocean).
When humans migrated across the Bering Strait to N America during the last Ice Age, they brought along domesticated dogs. Soon after, black coats appeared in the native Gray Wolf population, caused by increased melanin due to changes in a single gene.
Known as the K gene (Japanese kurokami for ‘black hair’), the dark coat resulted from a variant introduced by interbreeding with dogs. Wolves carrying one or two copies of the KB version are black.
The frequency of black wolves increases from the Arctic to Mexico. Black coats are more common in regions with canine distemper outbreaks. It turns out that the K gene is a natural antibiotic (“defensin”) that confers immunity against distemper.
But the black coat variant also carries a fitness defect: few pups with 2 copies survive to adulthood. Gray-coated wolves produce larger litters and are more aggressive than black-coated wolves during territorial conflicts.
We studied Mono Lake in my 6th grade class. It’s an interesting ecosystem because the lake doesn’t have any streams taking water away from the lake — it’s a dead end. Over the millennia the lake has gotten very salty, to the point where fish can’t live in it. But there are 2 varieties of algae, and they form the base of a somewhat small food web.
Back in 1913 the city of Los Angeles decided they needed the freshwater that was flowing into Mono Lake and others and built the largest gravity fed aqueduct to bring the water to LA. A lawsuit brought by the Mono Lake Committee managed to save Mono Lake, but not nearby Owens Lake, which dried up entirely. The agreement stipulated that LA would get 1/4 of the water going to the lake, and Mono Lake got the rest.
Sometimes when flying over the middle states, you might see something like this:
Some of the more comedic then say “Look! Crop Circles!” Well, yes, they are crops, and they are in circles, but these aren’t made of aliens. If you got down to the ground to view them close up, you’d see something like this:
So, how does that make the green circles? I’ve wanted to know more, and conveniently Destin at SmarterEveryDay just made this video that explains it really well: