Krejčí is rightly known as “the father of Czech geology”, of which he was the originator. However, he was also Jan a member of the revival movement and was a politician and popular teacher. He established Czech geological terminology and published summaries of contemporary scientific findings in Živa magazine, which he edited together with Jan Evangelista Purkyně. The foundations of Czech science that he laid in the second half of the 19th century influenced subsequent generations of scientists and teachers. In his work he draws on Charles Lyell’s modern concept of geology and the teachings of Darwin. As a field worker he was involved in the geological mapping of Bohemia and personally walked through most of the country’s geological areas.

Jan Krejčí was born in Klatovy as the only son of a former dragoon (a member of the mounted infantry). Soon afterwards his family moved to Prague to find work, and so young Jan went to school there. A key time in his life came when he was studying at the real grammar school in Prague, where one of his teachers was Josef Jungmann (credited with defining the rules for the standard Czech language), who became a great role model for him. His studies were interspersed with with revival parties associated mainly with Vojtěch Náprstek, which were held at the “U Halánků” house (now the Náprstek Museum). They organised trips to places around Prague, poetry readings and philosophical debates. At the end of his philosophical studies Krejčí was involved in the revolutionary events of 1848. After completing his studies he became an assistant at the Museum under Franz Xaver Maximilian Zippe; he followed up on his teacher’s ideas and after leaving for Vienna became the curator of the museum collections there. He taught at the real grammar school in Žitná Street in Prague, and later at the Prague polytechnic and the Prague university. He was also a member of the Landtag. Krejčí worked at a time when Czech scientific terminology was just becoming established. His work combines scientific findings with a comprehensible literary style, by which he wanted to make scientific discoveries accessible to his students as well as to the ordinary reader. He wrote textbooks and, together with Jan Evangelista Purkyně, became editor of Živa magazine. It was in this magazine that he gradually polished his literary and scientific style and his texts came to serve as the model for scientific writings in Czech. He wrote not only on geological topics, but also about physical phenomena and cosmogenesis; he also popularized Darwin's teachings on evolution (as a result of which he came into conflict with ecclesiastical dignitaries.) One interesting case is his professional dispute with Joachim Barrande. Barrande had discovered that in certain places geologically younger trilobites and other animals appeared amidst older fauna. He explained this as “colonies” of younger fauna, which appear in older formations and then gradually spread, or supplant the older fauna. Krejčí correctly pointed out that the presence of younger fauna amongst older fauna was caused by the presence of younger layers amidst older layers as the result of deformation during the process of orogeny. Eventually, however, he retracted this claim (even though it was true), evidently out of respect for the ageing Barrande. After all, there were concerns that Barrande, resentful about the dispute with the Czech scientific community, would not want to leave his extensive collection of fossils to the National Museum.

Krejčí wrote in an appealing style, which is still easy to understand for the modern reader. Besides his poetic Horopisné obrazy okolí pražského (Orographic Pictures from around Prague), where he describes the views from well-known peaks, which are now highly popular tourist destinations, he published a geology textbook and many enlightening articles in Živa. He died at the age of 62, after having caught cold on a geological excursion. After his death Czech geology underwent a period of stagnation and did not start to develop again until after the establishment of Czechoslovakia.

Connected places: Gustav Carl Laube
Antonín Frič
Joachime BarrandePamětní deska Jana Krejčího na Vyšehradě; Gustav Carl Laube