Researchers from the Kansas Geological Survey, based at the University of Kansas, have been drilling a half-mile-deep hole in southwestern Douglas County.

Their aim is to capture a continuous core of the rocks encountered during drilling, providing a complete record of the geologic history represented in those subsurface formations. The results also will provide a better understanding of water, natural gas and other natural resources in this part of the state.

Although shallow wells are regularly drilled in northeastern Kansas for water, and occasionally oil and gas, deep wells like this are rare. In addition, conventional drilling usually produces only small chips of the rocks encountered, as opposed to intact cores of rock, which give a much more complete picture of the subsurface.

The core drill brings up a pristine cylindrical piece of the earth that is an accurate representation of what rests beneath the surface. It works by cutting a doughnut-shaped hole into the earth with a diamond-studded drill bit. The drill cuts in 20-foot segments, and a long chain brings the core to the surface.

This will be among the first, and deepest, continuous core of rocks of this age in this part of the Midwest.

“These cores will be useful in many areas, from studying the potential for natural gas from coal layers to getting a better sense of deeper formations that contain saline water,” says geologist Dave Newell. “They will also tell us more about the time when these rocks were deposited, helping us understand ancient climates and forecast future climate changes.”

The well will be approximately 3,000 feet deep. Much of the time, it will drill through limestones, sandstones and shales deposited during the Pennsylvanian Period of geologic history, about 300 million years ago. During this time, northeastern Kansas was much closer to the equator, and was covered by a series of shallow, fluctuating seas.

“The rocks encountered in this well are from times that range from harsh desert settings to tropical marshes to large inland seas,” says geologist Lynn Watney.

The final few hundred feet will drill into Precambrian-age rocks that are as much as 1.67 billion years old. These are igneous and metamorphic rocks that are seldom sampled in Kansas because they are so deeply buried and generally don’t contain resources such as oil or water.

“These cores will tell us much about the makeup of these ancient Precambrian rocks,” says Watney. “In addition, these Precambrian rocks influence the rocks that are blanketed over the top of them, so learning about the Precambrian helps us learn about the nature and configuration of younger rocks above, which are a source of natural resources.”

Drilling began June 22 and lasted approximately two weeks.

“The results will be of value to geoscientists for years to come,” says Watney.