[Rockhounds] The strange race to track down a missing billion years

[Kreigh Tomaszewski]

A billion years have vanished from the geological record – and over 152
years after this was first discovered, scientists can't agree on why.

"FEARFUL DISASTER," read the headline
<https://chroniclingamerica.loc.gov/lccn/sn82014064/1869-07-03/ed-1/seq-1/#date1=1869&index=10&date2=1869&words=Major+Powell+Powells&searchType=basic&sequence=0&state=&rows=20&proxtext=Major+Powell&y=0&x=0&dateFilterType=yearRange&page=1>
on
the front page of the Chicago Tribune on 3 July 1869.

The paper was referring to an incident involving a motley team of explorers
led by the one-armed, self-taught geologist John Wesley Powell. Their
mission was simple, though not easy – to travel 1,000 miles (1,609km)
downstream from the banks of the Green River in Wyoming, cataloguing their
finds as they went.

It had been some weeks since anyone had heard from the party, and public
anxiety was mounting. Now a man claiming to be the sole survivor was
speaking to the press. The last time he had seen them, he said, Powell had
been standing on his boat, waving his hat in cheery farewell... just before
the whole expedition plunged directly into some deadly rapids. Hours later,
the narrator had found a lone carpet-bag floating down the river. It
contained Powell's notebooks.

In the week that followed, the tragic news was widely circulated. But
Powell's own wife was not convinced
<https://chroniclingamerica.loc.gov/lccn/sn82014064/1869-07-07/ed-1/seq-2/#date1=1869&index=1&date2=1869&words=Major+Powell&searchType=basic&sequence=0&state=&rows=20&proxtext=Major+Powell&y=0&x=0&dateFilterType=yearRange&page=1>
–
and it turned out she was quite right. It soon became clear that the source
had probably never even met Powell, let alone accompanied the expedition.
His whole story was entirely made-up.

At least, this is how it seemed at first. But then Powell discovered
something odd
<https://play.google.com/books/reader?id=wSY6orWMf5AC&pg=GBS.PA211-IA1&hl=en>
in
the bewildering height of the canyon walls.

Standing at the base of the cliffs and looking upwards, he could see a
thick section of hard, crystalline rocks – mostly granite and schist (slate
or shale that has been subjected to intense pressure), arranged in unusual
vertical layers. Above this was a 1,000ft (305m) band of reddish sandstone,
in the neat horizontal lines you would expect.

But here was the catch – by counting the layers of vertical crystalline
rock, Powell estimated that this section should be 10,000ft (3,050m) thick.
In reality, it measured just 500ft (152m). There were thousands of feet of
missing rock – it had just vanished. He named this feature The Great
Unconformity, and asked himself, "how can this be?".

https://www.bbc.com/future/article/20210901-the-strange-race-to-track-down-a-missing-billion-years