How to pronounce “brainteaser” in English

But most of the canyon itself was carved only in the past 5 to 6 million years by erosion from the Colorado River.It’s kind of a brainteaser— the Grand Canyon itself is much, much younger than even the youngest rocks it’s made of.Only in geology can something that happened 5 million years ago qualify as “recent history.” Also, sedimentary rocks hold clues to what a