Ancient cave rocks reveal impact of climate change
Minneapolis, Minn. — In a small office in an old lab on the U of M campus, Hai Cheng sorts through a cardboard box full of stalagmites from all over the world.
"Those are from Peru, and those dark-colored samples are from Turkey. This yellow one is from Ukraine. I collected that last summer."
Hai Cheng grew up in China, but now he's a research scientist in the Department of Geology and Geophysics at the University of Minnesota.
His stalagmites are six-inches to a foot long and just two or three inches wide. They look a little like agates. They've been split in half length-wise to expose wavy lines -- they're growth rings, like in a tree. Some of them are almost 1,000,000 years old. These ancient rocks are nature's time capsule, showing the ebb and flow of climate on the earth.