This research presents a novel approach to determine the relevant production ratio P21/P26 of the cosmic-ray-produced nuclides 21Ne and 26Al by isotopic measurements of Ne in quartz samples of glacially polished rocks of the Sierra Nevada range. The recently discovered cosmic-ray-produced radionuclides (10Be, 14C, 26Al, 36Cl) coupled with stable isotopes 3He, 21Ne, 22Ne and production ratios in terrestrial surface materials open up a new field of study which was not previously possible, e.g. determinations of erosion rates and geological processes (uplifts, variations in ice cover). Our feasibility study (Graf et al, 1991) has shown that cosmic-ray-produced Ne signatures in quartz can be recovered, and that determinations of the relative productions of 21Ne and 26Al (in both cases the target element is Si) will be required for the evaluation of complex exposure histories as are typical in geological processes, such as variations in the Antarctic ice cover.