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Why did the boundary between the Cambrian and Silurian systems cause a controversy?

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Cambrian paleogeography — Cambrian Period Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the late Cambrian Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.

The controversy regarding the boundary between the Cambrian and Silurian systems arose from a scientific feud between two prominent 19th-century geologists, Adam Sedgwick and Roderick Murchison.1

In 1835, Sedgwick named the Cambrian System based on his studies of rock successions in Wales, while Murchison simultaneously named the Silurian System based on his own fieldwork in the same region. As both geologists continued their research, they expanded their respective systems until they overlapped, leading to a dispute over the classification of the intervening rock strata.12

This conflict was eventually resolved by Charles Lapworth, who proposed the Ordovician System in 1879 to define the disputed overlapping interval. Although this compromise gained widespread international acceptance, it faced resistance in Britain for many years and was not officially adopted there until 1960.1