The 18th century saw the first attempts to find explanations for erratic boulders transported from distant sources, long esker chains, roche moutonnées, striae with a parallel orientation over large areas, and ancient shores, till and potholes - in other words, for features now explained by the Glacial theory published by Agassiz in 1840 and later supplemented by others. They were considered to be associated with a geological formation that had been called diluvium since the 1820s to distinguish it from young, alluvial deposits.

The following traces the views expressed on the diluvium of Finland from the early 19th century to the 1860s, at which time the Ice Age Theory supplanted rival concepts.

Scientists who had studied Finland attributed the diluvium to the Mosaic Deluge, other catastrophic floods, iceberg transport or large, sudden uplifts and the associated movement of water and earth masses. Of the views expressed by others than those who were studying Finland, the petridelaunian flood theory of Sefström had considerable influence. Boehtlingk based his explanations on a great upheaval of the Earth's crust and movements of earth masses. His ideas were elaborated by Murchison and Kutorga in their argumentation against the Ice Age Theory, which, to start with, was opposed chiefly by Sefström and Boehtlingk. Later two Finns, Holmberg and Nordenskiöld, published their own theories.

One of the first to accept the Ice Age Theory, Eichwald, was finally convinced some time before 1842. Moberg, a Finn, elaborated his own concepts from 1849 onwards, initially testing the theory of Sefström. Some other Finns were ready to accept the Glacial Theory in the late 1850s-early 1860s but were hesitant to abandon the old concepts.

In 1865, Moberg was ready to admit that the Glacial Theory offered the most natural explanation for diluvial phenomena. The debate about the validity of the theories, which had lasted for two decades, had prepared the ground for a dramatic wing in opinion. Before Moberg, the Glacial Theory was hardly mentioned in the literature; after his lecture of 1865, the old theories were not heard of again in geological studies in Finland.

It took a quarter of a century for the Glacial Theory to gain currency among scientists in Finland. It was not easy for them to abandon concepts that had been held for decades. A new generation was needed; one which did not feel it was losing its scientific clout by accepting new doctrines.

Geological Survey of Finland
Betonimiehenkuja 4
FIN-02150 ESPOO
FINLAND

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