A positive fold test and a negative conglomerate test help determine when and how stable remanence was acquired in the Middle Ordovician Table Head Group limestones of the Port au Port Peninsula of Newfoundland. The limestones magnetized after lithification and incorporation as clasts into a Middle Ordovician breccia. Hence, the limestones do not carry a detrital or other primary remanence despite their very low conodont colour alteration index of 1. The remanence may be thermoviscous or diagenetric and was acquired before Devonian folding. This suggests the need for caution interpreting paleomagnetic result from other early Paleozoic limestones whose remanence resides in magnetite of blocking temperature lower than 400 ¿C. ¿ American Geophysical Union 1989