Faunal, paleomagnetic, and sedimentological arguments that claim to show the existence of a continental ice sheet in northwest Africa during the Ordovician and Silurian are questionable. Neither the fauna nor the relevant pole positions necessitate the presence of land ice. The existing supposedly glacial level is of uppermost Ordovician age, and its lithological and other features do not necessarily involve glacial deposition. It seems to be related to tectonic movements reflecting the Taconic orogeny. An origin by mass-flow, in harmony with the available evidence, is suggested.

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