This action provides partial support for Accelerator-Based Mass Spectrometry (AMS) in the general applications area of the geosciences at the University of Rochester. AMS provides unique capabilities for measuring extremely small concentrations of isotopes in microsamples and is therefore a valuable technique for dating and tracer work using cosmogenic radioactive isotopes such as carbon-14, chlorine-36, beryllium-10, and aluminum-26. The Rochester AMS facility is the only one in the U.S. capable of making accurate chlorine-36 measurements, particularly useful in dating and tracing the flow of groundwater.