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Nanometer silica powders compacted at different pressures have been studied by atomic force microscopy (AFM). Local elastic moduli measurements made on the powder compacts yield values smaller than that of bulk silica. Loading force-distance curves measured show break points at some critical pressures. AFM images obtained at constant contact forces above and below the critical force at which a break point occured show the break point was a result of AFM tip plowing into the nanometer powder compacts. The applied force required for break points to occur increases with sample density. Such a behavior has been qualitatively explained in terms of adhesion force between nanoparticle and sample surface morphology.