Julius Kaljuvee, Ivan Reinwald, and Estonian pioneering ideas on meteorite impacts and cosmic neocatastrophism in the early 20th century

The article comprehensively presents little known Estonian contribution to the recognition of first meteorite impact structures in Europe, related to works of Julius Kaljuvee (Kalkun; 1869–1940) and Ivan Reinwald (Reinwaldt; 1878–1941). As an active educator specialized in geoscience, Kaljuvee was the first to hypothesize in 1922 that Kaali lake cirque in Saaremaa Island, Estonia, was created by meteorite impact. Thanks to mining engineer Reinwald, this assumption was accepted since 1928 due to the exhaustive field and borehole works of the latter (also as a result of exploration by several German scholars, including renowned Alfred Wegener). The impact origin of Kaali structure was proved finally in 1937 by finding of meteoritic iron splinters (as the first European site). Reinwald was not only outstanding investigator of meteorite cratering process, but also successful propagator of the Estonian discoveries in Anglophone mainstream science in 1930s. In addition, in his 1933 book, Kaljuvee first highlighted an impact explanation of enigmatic Ries structure in Bavaria, as well as probable magmatic activation in distant regions due to “the impulse of a giant meteorite”. He also outlined ideas of the inevitable periodic cosmic collisions in geological past (“rare event” theory nowadays), and resulting biotic crises. In a general conceptual context, the ideas of Kaljuvee were in noteworthy direct or indirect link with concepts of the great French naturalists – Laplace, Cuvier and Elie de Beaumont. However, some other Kaljuvee’s notions, albeit recurrent also later in geoscientific literature, are queer at the present time ( e.g. , the large-body impact as a driving force of continental drift and change the Earth axis, resulting in the Pleistocene glaciation). Thus, the Kaljuvee thought-provocative but premature dissertation is rather a record of distinguishing erudite activity, but not a real neocatastrophic landmark in geosciences history. Nevertheless, several concepts of Kaljuvee were revived as the key elements in the current geological paradigm.