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The alkali metals K, Rb and Cs, and the alkaline earth metals Ca, Sr and Ba were analyzed in the rocks, minerals, soils, snow, stream water and soil moisture films of Thompson Canyon, a glacially scoured watershed in the central crest region of the Sierra Nevada in east central California. The stable isotope dilution method was used. 1. The mass balance of metals entering and leaving the watershed, the denudation rate, and chemical and mineralogical details of the weathering process: In the batholithic source rock, two major minerals, microcline and plagioclase, and one minor mineral, biotite, contain most of the mass of the six metals. Snow is the main source of water to the valley, and contains much lower concentrations of metals than has been previously reported. These metals originate from distant sources. The mass of metals leaving the watershed annually in stream outflow indicates that the watershed is being denuded at a rate of less than 1 cm per 1000 yr, and that the principal process is chemical removal. Ca and Sr are being denuded more rapidly from the batholithic rock than the alkalies or Ba. This is shown by the greater proportion of Ca and Sr in stream water in contrast to the greater proportion of alkalies and Ba in the source rock. Rapid breakdown of plagioclase is responsible for this differential removal. In rock and grus, ratios among metals present in plagioclase (Ca and Sr) and those in K-feldspar (K and Ba) show that plagioclase is preferentially removed as rocks weather and crumble to grus. Rivulets running away from melting snow banks in mid summer dissolve large amounts of Ca and Sr at only short distances away from the snow banks, and hold these metals for transport out of the watershed. Particles from the snow banks, rich in Rb and Cs, similar in composition to mica, are deposited in soils by the rivulets. Comparison of metal compositions of rock and grus show that mica particles are freed as the rocks break down. 2. Metals in soils: Masses

The alkali metals K, Rb and Cs, and the alkaline earth metals Ca, Sr and Ba were analyzed in the rocks, minerals, soils, snow, stream water and soil moisture films of Thompson Canyon, a glacially scoured watershed in the central crest region of the Sierra Nevada in east central California. The stable isotope dilution method was used. 1. The mass balance of metals entering and leaving the watershed, the denudation rate, and chemical and mineralogical details of the weathering process: In the batholithic source rock, two major minerals, microcline and plagioclase, and one minor mineral, biotite, contain most of the mass of the six metals. Snow is the main source of water to the valley, and contains much lower concentrations of metals than has been previously reported. These metals originate from distant sources. The mass of metals leaving the watershed annually in stream outflow indicates that the watershed is being denuded at a rate of less than 1 cm per 1000 yr, and that the principal process is chemical removal. Ca and Sr are being denuded more rapidly from the batholithic rock than the alkalies or Ba. This is shown by the greater proportion of Ca and Sr in stream water in contrast to the greater proportion of alkalies and Ba in the source rock. Rapid breakdown of plagioclase is responsible for this differential removal. In rock and grus, ratios among metals present in plagioclase (Ca and Sr) and those in K-feldspar (K and Ba) show that plagioclase is preferentially removed as rocks weather and crumble to grus. Rivulets running away from melting snow banks in mid summer dissolve large amounts of Ca and Sr at only short distances away from the snow banks, and hold these metals for transport out of the watershed. Particles from the snow banks, rich in Rb and Cs, similar in composition to mica, are deposited in soils by the rivulets. Comparison of metal compositions of rock and grus show that mica particles are freed as the rocks break down. 2. Metals in soils: Masses

The alkali metals K, Rb and Cs, and the alkaline earth metals Ca, Sr and Ba were analyzed in the rocks, minerals, soils, snow, stream water and soil moisture films of Thompson Canyon, a glacially scoured watershed in the central crest region of the Sierra Nevada in east central California. The stable isotope dilution method was used. 1. The mass balance of metals entering and leaving the watershed, the denudation rate, and chemical and mineralogical details of the weathering process: In the batholithic source rock, two major minerals, microcline and plagioclase, and one minor mineral, biotite, contain most of the mass of the six metals. Snow is the main source of water to the valley, and contains much lower concentrations of metals than has been previously reported. These metals originate from distant sources. The mass of metals leaving the watershed annually in stream outflow indicates that the watershed is being denuded at a rate of less than 1 cm per 1000 yr, and that the principal process is chemical removal. Ca and Sr are being denuded more rapidly from the batholithic rock than the alkalies or Ba. This is shown by the greater proportion of Ca and Sr in stream water in contrast to the greater proportion of alkalies and Ba in the source rock. Rapid breakdown of plagioclase is responsible for this differential removal. In rock and grus, ratios among metals present in plagioclase (Ca and Sr) and those in K-feldspar (K and Ba) show that plagioclase is preferentially removed as rocks weather and crumble to grus. Rivulets running away from melting snow banks in mid summer dissolve large amounts of Ca and Sr at only short distances away from the snow banks, and hold these metals for transport out of the watershed. Particles from the snow banks, rich in Rb and Cs, similar in composition to mica, are deposited in soils by the rivulets. Comparison of metal compositions of rock and grus show that mica particles are freed as the rocks break down. 2. Metals in soils: Masses