At Bertram in Linn county and at Canton in Jackson county are found deposits of sandstone, shale and clay, called by courtesy outliers, though very limited in area and thickness, which carry Devonian fossils. Their importance lies in the fact that if their assignment to the Devonian by the writer in 1893 is correct, they imply a significant transgression of the Devonian sea over east central Iowa.
Proceedings of the Iowa Academy of Science
©1926 Iowa Academy of Science, Inc.
Norton, W. H.
"A Reconsideration of the Age of Certain Outliers in Linn and Jackson Counties,"
Proceedings of the Iowa Academy of Science, 33(1), 207-211.
Available at: https://scholarworks.uni.edu/pias/vol33/iss1/40