A paleomagnetic study of the Late Ordovician Thouars Massif reveals very steep components of magnetization, directed upward and downward, and with thermally discrete blocking temperature of 550¿C to 580¿C. This characteristic magnetization yields a mean direction with declination/inclination =340¿/-83¿, with k=27 and α95=7¿, based on 15 sites. The south paleopole is located at 34¿N, 5¿E. A partial magnetic overprint of Hercynian age is observed in sites close to the South Armorican Shear Zone. The 15 sites are spread over some 20 by 30 km, and the internal consistency of the site-mean directions indicates that differential tilting of parts of he massif has not occurred. Since it appears to be unlikely that the entire massif was tilted, we infer that the characteristic direction is primary and that the paleopole adequately represents the local magnetic field in the Late Ordovician. The palepoole for the Thouars Massif supports previously obtained results from other Ordovician rocks in Hercynian Europe, but it is the first result to pass modern reliability criteria. The high Ordovician paleolatitudes of the Armorican Massif, other areas in Heroynian Europe, and northwestern Africa, indicate that Gondwana and Armorica were adjacent until Late Ordovician time. Low paleolatitudes for Late Devonian time suggest that Armorica underwent rapid northward motion, at a rate of about 10 cm/yr, during the Silurian and earliest Devonian.

Armorica is thought to have collided with North America and the Baltic shield/Russian Platform before or during the Early devonian, forming the Old Red Continent. The collisions produced the Caledonian and Acadian orogenic belts.