Fossil shells and paleosol carbonate from ancestral Himalayan river deposits provide a Sr-87/Sr-86 record of lowland Himalayan river water during the late Neogene. Reconstructed Sr-87/Sr-86 river values increased sharply in the late Miocene, probably marking the beginning of exhumation of high Sr-87/Sr-86 metalimestones, more in the central than in the western Himalayas. These results imply that the marine Sr-87/Sr-86 record may not be a proxy for silicate weathering or consumption of atmospheric CO2 resulting from that weathering.