The Great Devonian Controversy began in 1834 when

Roderick Murchison Sir Roderick Impey Murchison, 1st Baronet (19 February 1792 – 22 October 1871) was a Scottish geologist who served as director-general of the British Geological Survey from 1855 until his death in 1871. He is noted for investigating and desc ...

disagreed with

Henry De la Beche Sir Henry Thomas De la Beche KCB, FRS (10 February 179613 April 1855) was an English geologist and palaeontologist, the first director of the Geological Survey of Great Britain, who helped pioneer early geological survey methods. He was the ...

as to the dating of certain petrified plants found in coals in the

Greywacke Greywacke or graywacke ( ) is a variety of sandstone generally characterized by its hardness (6–7 on Mohs scale), dark color, and Sorting (sediment), poorly sorted angular grains of quartz, feldspar, and small rock fragments or sand-size Lith ...

stratum in North

Devon Devon ( ; historically also known as Devonshire , ) is a ceremonial county in South West England. It is bordered by the Bristol Channel to the north, Somerset and Dorset to the east, the English Channel to the south, and Cornwall to the west ...

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

. De La Beche was claiming that since

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

fossils were found deep in the Greywacke stratum, which itself was older than the

period, this method of dating rocks was not valid. Murchison, in contrast, claimed that De La Beche had not placed the fossils correctly, as they were occurring quite near the top of the stratum as opposed to deep within it. De La Beche soon agreed with Murchison's argument as to the placing of fossils but maintained that since a layer of

Old Red Sandstone Old Red Sandstone, abbreviated ORS, is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the eastern seaboard of North America. It ...

, present in other formations, was missing between the layer of older rock and this new formation, there was still insufficient evidence to suggest the formation was not part of the older

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

strata. There followed much debate and some extensive investigations which ranged as far as Russia, where in 1840 Murchison discovered a layer similar to the one found in Devon placed between well-defined Silurian and Carboniferous deposits. This discovery put an end to the controversy and led to the definition of a new period called

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

Further reading