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Sept.18, 2013

Vol. 114, No. 1

Life of the Mind

Geoscience: Creative Destruction

To learn from the past, Adam Maloof must destroy it

By Kenneth Chang ’87
Published in the September18, 2013, issue

Adam Maloof prepares to grind a rock that records tidal cycles 640 million years ago.
Peter Murphy
Adam Maloof prepares to grind a rock that records tidal cycles 640 million years ago.

Fossils, ancient rocks, and rare meteorites millions or billions of years old — these are just some of the items that Adam Maloof, an associate professor of geosciences at Princeton, is looking forward to feeding to an automated industrial-scale machine that methodically, efficiently, and precisely grinds everything to dust.

“Just for fun,” he says, “we might try a dinosaur bone.”

With a high-pitched whir, the grinding began in earnest in July, obliterating a fossil of Cloudina, a reef-dwelling creature that lived about 550 million years ago.

But the goal is reconstruction and discovery, not desecration. While the end product is worthless, the journey of destroying everything will yield a trove of data to tackle geological and paleontological puzzles.

Maloof and an architecture firm, Situ Studio in Brooklyn, N.Y., have spent a couple of years working on GIRI — a friendly acronym for Grinding Imaging and Reconstruction Instrument. The new imaging laboratory has produced stunning three-dimensional views and revolutionized the way scientists can study rocks and other structures.

The impetus for the project came from an unusual rock in South Australia, where Maloof worked every summer between 2006 and 2011. He and a graduate student, Catherine Rose *12, were studying geologic formations from a time when glaciers reached the tropics. The rock, embedded with striking red shapes, intrigued them.

“I’ve never seen a rock like this anywhere else,” Maloof says. “We literally spent two years walking over that every day.”

The rock had formed out of sediments at the bottom of a tropical sea between 635 million and 660 million years ago, and the red shapes looked like they could be fossils of some very early sea creatures. They also could have been the product of some geological process unrelated to life, and many paleontologists thought that to be the likelier possibility.

Although life started on Earth more than 3 billion years ago, for most of that time, it consisted only of microscopic single-cell organisms. Only later, about 540 million years ago, did more complex animals such as insect-like marine creatures called trilobites arise, a proliferation of species known as the Cambrian Explosion.

That evolutionary transition from single-cell microorganisms to more complex, multicellular animals with hard shells and bones is still murky. Fossils of these creatures are made of pretty much the same stuff as the rock that encases them, which makes it difficult to identify them as fossils and even harder to extract and study them.

“Who knows what these early forms looked like?” Maloof says.

The usual tools of imaging — shooting X-rays or electrons through the sample and observing how they are deflected — are not of much help because there is little variation in density or mineralogy between the fossils and the rocks.

With no easy way to study the strange Australian rock, no one studied it. “It had just been sitting there in a national park, not talked about,” Maloof says. Yet the red shapes were clearly visible, and Maloof turned to a more direct avenue of exploration: grinding.

The shapes seen on the surface of the rock represent two-dimensional cross sections of whatever was embedded inside. These cross sections tell, at best, an incomplete story. A circular cross section, for example, could be a slice of a sphere, but it also could be a slice of a cylinder. The different red shapes could be separate objects, or they could be connected as part of one structure. Grinding the rock, layer by layer, would reveal a series of cross sections, which could be stitched together to reveal the hidden three-dimensional shape.

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