During the summer of 1914 a considerable amount of grading was done at the forks of the road on the west side of Lora Hill, seven miles west of Dubuque. As a result of this work there was exposed along the road a band of peculiar reddish clay from one to two feet in thickness, underlain by the characteristic gray-green, plastic clay-shales of the Upper Maquoketa formation. The red clay is much less plastic than the underlying green shales, but is remarkable chiefly for the fact that it is composed largely of iron oxide and contains great numbers of small, rounded concretions or oölites. Also imbedded in this deep red clay are: a. numerous pebbles of smooth, polished chert, b. rounded fragments of indurated material similar to that of the clay, and c. rounded fragments of slightly iron stained shale.
Proceedings of the Iowa Academy of Science
©1916 Iowa Academy of Science, Inc.
Howell, Jesse V.
"An Outlier of the So-Called Clinton Formation in Dubuque County, Iowa,"
Proceedings of the Iowa Academy of Science, 23(1), 121-124.
Available at: https://scholarworks.uni.edu/pias/vol23/iss1/19