Having access to equipment like this is really something.... Getting this kind of hands-on experience makes students especially well prepared for graduate school.

Chris Daniel

Professor Chris Daniel, geology, likes to tell his students that rocks are like people: They all have a story to tell. It's just that some rocks take a little more work to tease the story out of than others.

But tease the story out they do – and some of these rocks have stories that span 1.4 billion years or more.

Using an extraordinarily powerful environmental scanning electron microscope (ESEM) allows Daniel and his students to study the chemistry and crystal structure of minerals within a rock, giving them more clues regarding its formation. This geochemical method helps them determine the temperature at which a rock was formed and the depth at which it was buried. The group then further pinpoints its age through uranium-lead dating.

"Having access to equipment like this is really something." Daniel explains. "Many institutions don't have an ESEM, and when they do, there are often additional fees for students to use it. Here at Bucknell, our students use them for no additional charge. Getting this kind of hands-on experience makes them especially well prepared for graduate school." 

Daniel demonstrates the capabilities of the ESEM using grains of crushed rock that are imperceptible to the naked eye. Under the microscope, crystal structure appears as banding lines, not unlike the rings that form in trees over time. "The ESEM is capable of 100,000 times magnification," he says, replacing the rock grains with a moth. "But 6,000 times magnification can also be very impressive." Under the microscope, the moth's eyes are revealed as a seemingly infinite pattern of hexagons. Its wings, too, are magnificent, as are the individual hairs that sprout from its head. 

Daniel's particular area of research is the Precambrian geology of the southwest United States with an emphasis on New Mexico, a destination to which he and his students routinely travel for research. The rocks that most interest them are metamorphic in nature, recrystallizing some ten to thirty kilometers beneath the surface at temperatures that range from 300 to 700 degrees Celsius.

Luckily for Daniel and his team, millions of years of pressure have forced these rocks to the surface where erosion has exposed them and made them relatively easy to collect.

Getting the rocks to tell the story of our continent's formation and evolution is the next challenge, he says.

Posted September 26, 2013