Lesley, J. Peter

(b. Philadelphila, Pennsylvanis, 17 September 1819; d. Milton, Massachusetts, 1 June 1903),

geology

Fourth in a line of Peter Lesleys and first son of Peter III and Elizabeth Oswald Allen, Peter Lesley was a delicate, introverted, and bookish youngster. He entered the University of Pennsylvania at fifteen and graduated Phi Beta Kappa in 1838. Frail health frustrated his plans to continue directly in school studying for the Presbyterian ministry, so at his father’s urging he sought outdoor employment. He joined the first state survey of Pennsylvania, directed by Henry Darwin Rogers, and passed the years 1838–1841 surveying the bituminous and anthracite coal regions.

Although he was untrained and inexperienced when he entered fieldwork, his insights into the complicated geology of the state won him Rogers’ praise. When in 1841 the survey was abandoned for lack of funds, Lesley returned to his studies at Princeton Theological Seminary. He maintained contact with Rogers, however, and when the Seminary was in recess he helped him with the preparation of maps and sections for the final survey report.

Lesley was licensed to preach by the Philadelphia Presbytery in 1844 and took up pastoral work the following year after traveling in Europe. He began his brief career in the ministry as an avowed conservative on questions of religious doctrine. Subsequent exposure to the liberal opinions of Rogers, Agassiz, Emerson, Lyell, and other associates in Boston, where he had gone to assist Rogers, radicalized the young clergyman to such an extent that he gave up the ministry altogether and became a geologist in 1852.

His first book, A Manual of Coal and Its Topography, has been called “the most important matter of the decade, geographically considered” (Davis [1919], 183). It is an attempt to group the Appalachian coal beds systematically, to correlate them with coal measures in Europe and elsewhere, and to emphasize the importance of topographical geology in Pennsylvania. Lesley proffered a catastrophic explanation of Appalachian landforms, although in later works, when his break with the ministry was not so fresh, this approach was replaced by uniformitarianism.

His second major work, The Iron Manufacturers’ Guide (1859), contains information and statistics on ironworks as well as a detailed geological discussion of iron deposits in Pennsylvania and elsewhere. The preface is notable for its intemperate personal attack on Rogers, who, Lesley felt, had failed to credit his young apprentices on the first state survey. Accusing Rogers of scientific theft and labeling him an “imposture,” Lesley sought to rectify the indignity of being mentioned only briefly in Roger’s preface.

When in 1873 he himself became director of the second state survey, Lesley was careful to see that each fieldworker be given due credit for his work. He often altered field reports and maps or added footnotes to his apprentices’ texts before sending them to press; he felt that doing so would clarify the material and protect the authors from unfavorable criticism. Lesley’s practice caused understandable consternation among his staff. As director of the survey he examined every line, map, and illustration in the seventy-seven volumes of text and thirty-four atlases. Lesley attempted to distill all this for the final summary, but his health broke under the strain and he was forced to delegate responsibility to others.

Although christened Peter Lesley, he disliked his first name and in 1850 added the initial “J.” from “Junior” and began signing his work “J. P. Lesley.” Toward the end of his life he reverted to J. Peter Lesley.

BIBLIOGRAPHY

I. Original Works. Lesley’s most important contributions are A Manual of Coal and Its Topography(Philadelphia, 1856); The Iron Manufacturers’ Guide to Furnaces, Forges and Rollings Mills of the United States (New York, 1859); and the Second Geological Survey of Pennsylvania Report: A Historical Sketch of Geological Explorations in Pennsylvania and Other States (Harrisburg, Pa., 1876); and Final Report: A summary Description of the Geology of Pennsylvania, 3 vols. (1892–1895).

II. Secondary Literature. a two-volume biography was edited by his eldest daughter, Mary Lesley Ames, as Life and Letters of Peter and Susan Lesley (New York, 1909). For biographical notices see W. M. Davis, “Biographical Memoir of J. P. Lesley,” in Biographical Memoirs. National Academy of Science, 8 (1919), 152–240; P. Frazer, “J. Peter Lesley,” in American Geologist, 32 (1903), 133–136; A. Geikie, “Notice of J. P. Lesley,” in Quarterly Journal of the Geological Society of London, 60 (1904), xlix–1v; B. S. Lyman, “Biographical Sketch of J. Peter Lesley,” in Transactions of the American Institute of Mining Engineers, 34 (1903), 726–739; G. P. Merrill, “Peter Lesley,” in Dictionary of American Biography; and J. J. Stevenson, “Memoir of J. Peter Lesley,” in Bulletin of he Geological Society of America, 15 (1904), 532–541.

Martha B. Kendall