Geologists converge on Missouri Breaks to study lava formations

Tim Leeds Havre Daily News [email protected]

Major geologists from around the world are coming to the Upper Missouri River Breaks for about 10 days to study some fairly unique lava formations in the Breaks. “There are still a lot of mysteries to solve,” said Carter Hearn of McLean, Va., who is guiding the work in the Breaks over the next 10 days or so. Hearn said the group of 10 geologists he will be taking to the formations is from around the world some are Canadian students, but others are established geologists from Canada, Germany, France and New Zealand. After that group is done, he said, he will work with another smaller group for a few days as well. Hearn, a retired geologist with the U.S. Geological Survey, still works for the USGS and also works as a curator for the Smithsonian Institute of Natural History. Many of the rocks and formations he curates at the Smithsonian are very similar to rare and unusual rocks in the Bear 's Paw Mountains and the Highwood Mountains, Hearn added. The lava pipes in the Breaks allow valuable study in the formation of the pipes, or diatremes relatively rare formations where lava comes from deep beneath the earth's surface, pushing up and typically forming a depression or small cone. Hearn said the research on the volcanic pipes helps determine how small, explosive volcanoes evolve, although the study of the pipes is not directly related to large volcanic eruptions. That limits how helpful it is to working on the hazards of volcanoes. A major benefit is in studying what the lava brings with it, Hearn said. The pipes have rocks around them brought up from deep beneath inside the earth. “These are rocks we never get to see at the surface except in (volcanic pipes,)” Hearn said. The pipes also bring fossils to the surface. “It's been interesting to paleontologists,” Hearn said. Study of the pipes in the Breaks also has an economic benefit, he added. The pipes are similar to kimberlite volcanic pipes, in which most significant diamond deposits in the world have been found. Some of the pipes in north-central Montana have been tested for diamonds, although they have not been found. Studying the pipes helps in the study of the kimberlites, increasing the understanding of the formation of the diamonds and other gems such as garnets, and how to find and mine the gems. Hearn said the formations will provide an excellent opportunity for the geologists to study the pipes. “There will be interesting discussions and probably some controversy,” he said. The Bear's Paw Mountains and the Missouri Breaks provide many interesting sites for geologists, said Hearn, who did his thesis for his PhD in geology in 1955 at Johns Hopkins University in Baltimore mapping geological formations in a quadrant of the Bear Paws south of Cleveland. The mountains themselves, of volcanic origin about 49 million to 52 million years old, expose many features not normally found, Hearn said. The lava that formed the mountains slid off to the north and south, exposing rock and fossils pushed up from deeper in the earth, Hearn said. He said he began working in the area with geologist Bill Pecora, who mapped formations in the area between 1948 and 1962. Many students came to work with him over those years, Hearn said.