Thomas Benton Brooks is pictured. (Photo courtesy of the Marquette Regional History Center)

Shortly after the U.S. Civil War ended, Maj. Thomas Benton Brooks moved to the Marquette Iron Range from New Jersey. There, over the course of less than a decade, he became a prominent geologist, prospector, mining and civil engineer, and mining company executive in the region.

During these formative years of the iron ore industry, when the Lake Superior region was providing about one-quarter of the iron ore used in the U.S., he was employed by the Iron Cliffs Company, a predecessor of Cleveland-Cliffs Inc., the Michigan and Wisconsin Geological Surveys and served as a consultant mining companies and investors.

He had a significant role in identifying and mapping the geology, iron ranges and ore deposits in Michigan and Wisconsin and his contributions had a lasting impact on iron ore mining in the region.

Major Brooks was born on June 15, 1836 in Monroe, New York, near the New Jersey border. In 1852, he joined a surveying crew and the next year was employed by the New York Topographic and Geological Survey.This lead to his enrollment in the engineering program at Union College in Schenectady, New York in 1856, from which he graduated in 1858 in civil engineering.

After teaching engineering at Union College, he volunteered for the Union Army in 1861 and organized an engineering company that had a distinguished record during numerous Civil War campaigns. He retired from the Union Army in 1864 as a brevet colonel after being wounded at the second Battle of Drewry’s Bluff, also called the Battle of Proctor’s Creek, which was part of the Bermuda Hundred Campaign in Virginia, but referred to himself after the war simply as Major Brooks. (A brevet is a commission given to a military officer with a higher named rank, but they did not receive any extra pay.)

In 1864, after leaving the Union Army, Brooks accepted a position with the Geological Survey of New Jersey where he conducted magnetic surveys to locate iron ores and was put in charge of mines and furnaces. Shortly thereafter, he took charge of the mines of the Iron Cliffs Company on the Marquette Iron Range as vice-president and general manager.

He moved to Negaunee where his practical knowledge of geology and engineering, leadership skills, originality, keen powers of observation and deduction and intense work ethic served him, the company, and the Lake Superior region so very well.

This is where Brooks’ extensive geological studies began and where he refined the instruments and methodology that became the norm to exploit the iron ores of the Lake Superior region.

He brought the concept of the dip needle to the Lake Superior region and was the very first to use it in iron ore exploration and geologic mapping in the area. His first instrument in the Lake Superior region was home-made.

He also pioneered the dial (sun) compass, which he modified for geologic use from the surveying solar compass developed by W.A. Burt which was used to discover the first iron-rich rocks of the region near Negaunee.

A dip needle or dip compass measures the magnitude of the magnetic field by the equilibrium angle of a counterbalanced magnetic field rotating on a horizontal access.

It is used to identify the location and map iron formations and ores. A dial compass is a combination of a portable sun dial and a magnetic compass, used for mapping nearby geologic magnetic sources.)

In 1868, Brooks resigned from the Iron Cliffs Company. Next, he was given the responsibility of mapping and reporting on the Marquette Iron Range and was placed in charge of the Economic State Geological Survey of the district by the Michigan Geological Survey, essentially becoming the unofficial state geologist of the Upper Peninsula.

He received no salary for this position, but he was allowed to receive private funds from numerous iron ore companies and mines which he advised.

Unfortunately, his intense work schedule took a toll on his health that caused him to leave Marquette with his family in the winter of 1872-73 for London, England, and eventually Dresden, Germany, where he hoped to regain his health, but failed to do so.

During this period, he prepared reports on his iron range geologic studies for publication by the Michigan and Wisconsin Geological Surveys, articles on the geology of the region and magnetic surveying instruments and their use published in various journals and he co-authored the book, “Iron Ores of Missouri and Michigan.”

In addition to his geological studies and development of magnetic exploration instruments, Brooks’ engineering knowledge had an important role in developing safe, efficient methods of mining iron ores.

In the Lake Superior region, he established the first iron assay laboratory in the region and had a significant role in geological studies related to the copper ores of the Keweenaw peninsula.

Maj. Thomas B. Brooks was a truly outstanding pioneering geologist and engineer of the Marquette Iron Range and the Upper Peninsula of Michigan. He died near his hometown in New York on Nov. 22, 1900.

For more information on the life and accomplishments of Maj. Brooks, activate https://hdl.handle.net/11299/241950 or the Nov. 29, 1900 issue of The Daily Mining Journal for his obituary written by Charles A. Lawton.