Saw-tooth pattern of the Earth's magnetic field tested by magnetic anomalies over oceanic spreading ridges

In order to test the possible saw-tooth behaviour of the Earth's magnetic f ield during stable polarity intervals, we selected several magnetic profile s over the East Indian Ridge, the Juan de Fuca Ridge and the East Pacific R ise. We then compared the stacked magnetic anomaly profiles with different models. It appears that neither the uniform pattern nor the saw-tooth patte rn fully explain the shape of all anomalies. We propose a new magnetic held model with a gradual transition between Gauss and Matuyama periods and sma ller intensities for some short episodes. ((C) 1999 Academie des sciences/ Editions scientifiques et medicales Elsevier SAS.).