J. Harlen Bretz

1882 to 1981
Geological Mapping and Geological Processes

J Harlen BretzJ. Harlen Bretz was born on September 2, 1882, in Saranac, Michigan. He attended Albion College where he studied biology and met classmate Fannie Chalis. He married her in 1906. As a high school teacher in Seattle, Bretz developed an avid interest in the geology of Puget Sound. He entered the University of Chicago and completed his Ph.D. in 1913 with a thesis in glacial geology. After teaching geology at the University of Washington, he joined the faculty at the University of Chicago.

Beginning in 1922 and for the next seven summers, Bretz conducted fieldwork with his students in the Channeled Scablands of eastern Washington. Bretz published a controversial paper in 1923 in which he theorized that massive flooding in the distant past formed these Scablands. Ultimately, after 40 years, Bretz won over the many disbelievers of his catastrophic theory. Bretz, along with others, presented convincing field evidence of the Scablands formation about 15,000 years ago when cataclysmic flooding and erosion accompanied a massive wall of water and raging torrents from Glacial Lake Missoula. The Lake, covering much of western Montana, disgorged huge volumes of water when a glacial dam failed, sending the wall of water and torrents over the Columbia Basin and down the Columbia River Gorge, leaving behind deeply trenched channelways.

Even earlier, Bretz initiated summer work with the Illinois State Geological Survey. He published his first geological quadrangle map in Illinois in 1923. He again undertook geologic studies and mapping for the Survey in the 1930s, mapping both bedrock and surficial deposits in and around Chicago. To accompany his notable report, Geology of the Chicago Region in 1939, Bretz published a series of geological quadrangle maps in 1943. He provided an update with maps of the Pleistocene in 1955. In his monographs on Chicago, Bretz gave an ingenious analysis of the drainage of yet another glacial lake, Glacial Lake Chicago, the predecessor of modern Lake Michigan. Ancient shorelines indicated that the glacial lake once covered much of Chicago well beyond present Lake Michigan. Bretz' maps and information have been used widely in urban planning in the Chicago metropolitan area.

Bretz also was known as a world authority on caves and their formation. His research included the formation of caves in Illinois. He published several articles on this topic, including one by the Illinois State Geological Survey in 1961 summarizing caves in Illinois. Even after his retirement from the University of Chicago, he remained active. In 1979, at the age of 97, he was awarded the Penrose Medal of Honor, the Geological Society of America's highest honor.

Honored by: 
Morris M. Leighton's sons, F. Beach Leighton, Morris W. Leighton, and Richard T. Leighton
Citation Contributed by: 
Morris W. Leighton