The American geologist J.P. Lesley’s career began with a degree from the University of Pennsylvania in 1838. After helping Henry D. Rogers’ work with the Geological Survey of Pennsylvania for three years, he enrolled in the Princeton Theological Seminary from which he graduated with a licence to preach in 1844. There followed a year at Martin-Luther University in Halle-Wittenberg, Germany and more work with Rogers, as well as two years with the American Tract Society. In 1847 he became pastor of a Congregational church in Milton, Massachusetts, but four years later, in 1851, he had a change of heart, becoming a Unitarian: he left the ministry and moved back to Philadelphia with his family to spend the rest of his life doing geological research in the United States and Canada. As a consulting geologist he also went to Europe in 1863 to examine the Bessemer Iron Works in Sheffield, England, and to the 1867 Paris World Fair as one of ten commissioners sent by the United States Senate. He taught geology at the University of Pennsylvania from 1872 to 1885 and as an emeritus professor the following year. He became state geologist of Pennsylvania in 1874.
Despite these responsibilities, he found time to write many reports, papers and books on geology, and on iron and coal in particular. In addition, he was secretary and librarian of the American Philosophical Society from 1858 to 1885 and was one of the original members of the National Academy of Science. In 1884 he became president of the American Association for the Advancement of Science. George Mercer Dawson wrote his obituary in 1903 for the Transactions of the American Philosophical Society.

Léo Lesquereux, a palaeobotanist, grew up in Fleurier, a small Swiss town where his father was one of a Huguenot community of watchmakers. Young Leo loved roaming the cliffs and bogs of the region. At age seven, one of his explorations ended in a fall from a precipice; he survived but spent two weeks in a coma. He nevertheless persisted in his interest in bogs and devised a sort of augur to investigate their stratification that led to an understanding of the causes of peat formation and eventually to its relationship to the geology of coal.
He went to the University of Neuchatel where his theory met with skepticism but where he benefitted from the teaching of Louis Agassiz. He was appointed to chair at La Chaux de Fonds when tragedy struck: a Parisian doctor bungled treatment of an ear infection, leaving Lesguereux stone deaf for life and unemployed. He fell back on the family métier of watch-engraving but soon became despondent. His wife, the daughter of a Prussian general, not only nursed him but taught herself watch-engraving to support the family. After his recovery, he taught himself to lip-read in French, English and German so well that people often did not realize he was deaf.
His fortunes turned when the king of Prussia commissioned him to report on the peat bogs of the kingdom. He also examined bogs in the United States and Canada, and decided to follow his former teacher Agassiz to North America. He and his family moved to Columbus, Ohio, in 1848 where he began a watch business with his sons. Though poor at first, he was soon doing well enough to devote his energies to science. He became recognized as a pioneer of palaeobotany, contributing 12 important works. He was elected a member of the American Philosophical Society in 1861 and of the National Academy of Sciences in 1864. At his death in 1883 at the age of 83, J. P. Lesley wrote his obituary for the Proceedings of the American Philosophical Society.