IGS Geologists Reach New Heights in Limestone Research

by Brian Keith and Todd Thompson

Photo by John Day

The sawed walls in the dimension stone quarries of Monroe and Lawrence Counties are great places to study detailed features in the Salem Limestone. They can also be challenging places for geologists to work when quarry operators cut down multiple levels, leaving high walls behind. IGS geologists Brian Keith and Todd Thompson have been working in the quarries for many years as part of their research on understanding how the Salem developed into a unique deposit that is used as dimension stone, and which is also a petroleum reservoir in the subsurface. They saw an opportunity at Maple Hill Quarry to gain a true 3-D picture of the internal features of the Salem when the operator, Hoadley Quarries of Bloomington, cut a deep pit with exposed walls at right angles.

At left—IGS geologist Todd Thompson maneuvers the boom basket into position for photographing the quarry walls.
Photo by John Day

Keith and Thompson worked with Hoadley and the federal Mine Safety Administration (MSHA), which regulates safe operations in mines and quarries, to use a 60-foot telescoping boom lift to gain safe access to the upper quarry walls. Along with IU Geosciences graduate student Will Tackaberry, they received training to become qualified boom lift operators.

At right—The lift makes it possible for the geologists to study areas of the quarry walls that would otherwise be inaccessible or dangerous to reach.
Photo by Brian Keith

They were then able to outline features of the limestone using sidewalk chalk, take samples from the wall for analysis, and take digital photos all while using the boom. At the office, this information will be assembled into a 3-D image, showing the stone's characteristics—a truly "uplifting" experience for the geologists.

For more information about this research, see Sidewalk Chalk and Digital Technology? in the Winter 2002 edition of the IGS newsletter, GeoNews.

At left—Sidewalk chalk is used to outline features in the rock.
Photo by Todd Thompson