The scope of his examination was then enlarged so as to embrace a fuller survey of portions of the Northwest Territory, lying mainly within the present States of Wisconsin, Iowa, and Minnesota. This task required five years of field work and a final year of laboratory and office work, ending with the year 1852. A large appropriation was made by Congress for illustrating and printing Owen's report, all the details of publication being committed to him. The result was a finely illustrated quarto volume of six hundred and thirty-eight pages, many of the illustrations being from the original drawings of Dr. Owen, who had great facility in sketching. In this volume he applied for the first time the medal-ruling style of engraving to cuts of fossils.
In an article on Geological Surveys in Missouri Mr. Arthur Winslow says of Owen's reports up to this time: "These reports supplied the guiding lines along which later stratigraphic work in the Mississippi Valley was done. Without attempting here to present the history of this work, its bearing upon the future work in Missouri calls for brief mention. In the Indiana reports Owen makes a separation of the rocks, in harmony with the English classification, into 1. Bituminous coal formations. 2. Mountain limestone. 3. Grauwacke. 4. Crystalline and inferior stratified rocks. In the succeeding reports, as the results of wider observation and more thorough study, the classification was changed and differentiated until, in the final report, we find a classification which, not only in its general features, but in many of its details, is still adhered to in Missouri."
From 1854 to 1859 Dr. Owen was occupied with the geological survey of Kentucky, having been appointed State Geologist by Governor Powell. The results of his explorations were published as the work progressed, and compose four large octavo volumes. Dr. Robert Peter, of Lexington, Ky., performed the chemical work of the survey and made a special report upon it.
Toward the close of his labors in Kentucky, in October, 1857, Dr. Owen was commissioned to conduct a geological survey of the State of Arkansas. His principal assistant in the Kentucky survey, Mr. E. T. Cox, filled the same position in the new work. The chemical assistant on the latter survey was Dr. Elderhorst, author of a work on the blowpipe. Various incidents in his several surveys prove Dr. Owen to have been a man of indomitable perseverance. Once, while on the Red River of the North with a Canadian voyageur, the fowling-piece used by the latter for procuring game was discharged in such a way as to lodge a number of shot in Dr. Owen's shoulder. But he did not permit the accident to delay him an hour. Again, the summer occupied with the field work of the Arkansas survey, a considerable part of which was necessarily spent in the rich and malarious bottom lands.
