An archaeomagnetic study of hearths dated at 12,000 B.P. Indicates that the earth's magnetic field differed little from its present position. These new data support doubts which exist about the reality of the Gottenburg excursion. They also suggest that the radiocarbon time-scale for the period before 7000 B. P. May be more accurate than for the period 6500-4500 B.P. Information was also obtained about temperatures, temperature gradients and movement of hearth stones in Magdalenian times.