It's well known that when it comes to oil, the Middle East is king. Saudi Arabia has more than 260 billion barrels of proven reserves. Iran has 136 billion.
Iraq and Kuwait together nearly 120 billion. Combined, Middle Eastern reserves account for about forty percent of the world's known oil.
Which is odd, because the fossils that make up fossil fuels come mainly from ancient microscopic organisms that sank to the bottom of the ocean.
Those on the bottom of the pile were pushed down into the earth's crust and slowly cooked into crude.
But if oil comes from ocean dwelling organisms, you may ask, why is so much of it concentrated in the dry, arid Middle East?
Always A Desert?
Because, as you may have guessed, the Middle East was not always a vast desert.
Around 100 million years ago the region was covered by what scientists call the Tethys Ocean. Rivers feeding this ancient ocean saturated it with nutrients, giving rise to massive numbers of microscopic animals destined to be pressure cooked into oil.
The Tethys eventually receded and gave way to the sandy Middle East we know today. But it left behind a reminder of the area's watery past in the form of vast oceans of oil buried beneath the sand.
Read More: Tracing Oil Reserves to Their Tiny Origins (The New York Times)