Aleksander Piotr Czekanowski, or Aleksandr Lavrentyevich Chekanovsky (Russian: Александр Лаврентьевич Чекановский, 24 February 1833 – 30 October 1876) was a Polish geologist and explorer of Siberia[1][2] during his exile after participating in the January Uprising.
While there he also attended lectures on natural science and participated in local field trips during which he developed a strong interest in geology.
After graduating in 1857 he returned to Kiev where he started working at Siemens and Halske, which was at the time engaged in the construction of a telegraph line from Russia to India.
Accused of participating in the uprising, Czekanowski was arrested and sentenced to indefinite exile in Siberia, whereupon he was sent on foot from Kiev to Tobolsk.
Having had a business trip Academy of Sciences to Siberia, found out about the fate of Chekanovski in Irkutsk and informed prominent scientists in St Petersburg.
After using all his influence for two years, he obtained from the authorities the release of Czekanowski, his transfer from Padun to Irkutsk, and assignment to the Siberian Department of the Russian Geographical Society.
In 1872, Czekanowski proposed to the Geographical Society to explore the area between Yenisei and Lena, which at the time was still a "big white spot" in terms of hyrodgraphy and relief.
The company commissioned him to lead a small research expedition lasting two years, to which Ferdinand Ferdinandovich Miller was appointed to its staff as astronomer and physicist.
Over the three summer months of 1873, travellers traced the entire course of the Lower Tunguska to its mouth, plotting it on a map and determining its length (2989 km).
On 25 December 1873 Czekanowski and Miller left Irkutsk with two local guides travelled to Dolna Tunguska and proceeded on to 63º N, before continuing north-northwest to reach the springs of the river Vilyuy (66°00′N 104°00′E / 66.000°N 104.000°E / 66.000; 104.000).
Czekanowski established that there are no high mountains along the Olenyok, and according to his definition, the length of the river was about 2350 kilometres (according to the latest data – 2292 kilometers).
He hoped to have time to conduct geological exploration of the banks of the Lena River before the onset of winter, but a short summer frustrated his plans.
In this way he discovered a 350 kilometres (220 mi) long ridge (highest point 432 metres (1,417 ft)), which was later named Chekanovski at the suggestion of Edward Toll.
In the same year, he presented to the Academy of Sciences a project of an expedition in which he set out to geologically explore all the large Siberian rivers in the territory between the Yenisei, Lena, Anabar, Khatanga and Pyasina.
This provoked an exacerbation of his mental disorder and on October 18 (30), 1876 Czekanowski committed suicide by taking a large dose of poison.
In his honour the extinct ginkgo of the genus Czekanowskia[3][4] and an early Triassic ammonite Prosphingites Czekanowskii[5] from the Jurassic period.