In 1926, Clark began a major project to map the geology of the Quebec Appalachian Mountains along the U.S. border in the Eastern Townships. He published a series of papers on the geology and paleontology of the Townships.
Clark embarked on a major undertaking in 1926 to create a geological map of the Quebec Appalachian Mountains along the U.S.-Canada border in the Eastern Townships. He subsequently published a collection of papers detailing the region's geology and fossil history.