Fossil shells and paleosol carbonate from ancestral Himalayan river de
posits provide a Sr-87/Sr-86 record of lowland Himalayan river water d
uring the late Neogene. Reconstructed Sr-87/Sr-86 river values increas
ed sharply in the late Miocene, probably marking the beginning of exhu
mation 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-8
6 record may not be a proxy for silicate weathering or consumption of
atmospheric CO2 resulting from that weathering.