Isostasy of the Northern Bay of Biscay continental margin

Spectral analysis of eight marine gravity profiles and seven SEASAT profiles, combined with corresponding bathymetric data over the Northern Bay of Biscay origin, yield identical admittance functions for wavelengths greater than 120 km. The resulting admittance function has been interpreted in terms of an Airy model of compensation for wavelengths greater than 250 km and in terms of an elastic plate model of compensation for shorter wavelengths. Thehe Airy model corresponds to a crustal thickness variation across the margin. Thehe plate model with an elastic thickness of 8 km is associated with the regional compensation of a sedimentary load which was probably emplaced during and just after rifting.