A search has been made for variations in the 10Be concentration in a North Pacific marine sediment core during the period of a geomagnetic reversal. The 10Be was counted directly using an accelerator technique, thus permitting an order of magnitude improvement in time resolution compared to earlier 10Be measurements. No significant 10Be variations were seen, and several possible reasons are discussed. The measured 10Be deposition rate is substantially larger than in any previously studied sediment.