Fig. 4. X-ray diffractograms for oriented Mg2+-saturated 25°C silt fractions from subsurface horizons of each biome along an elevation and climate gradient on andesite parent materials in the Sierra Nevada, California. The horizons shown from each respective biome are: AL-7, A2; SA-6, A2; RF-5, Bw1; WF-4, Bw1; PP-3, Bt1; PO-2, Bt1; and BO-1, Bw1. The break between PP-3 and WF-4 represents the transition from rain-dominated systems to snow-dominated systems. Drop lines are in nanometers; unlabeled peaks dominantly derive from feldspars.