He teaches Geology, Ecology, Biodiversity and Biology at Friends School in Baltimore full time. In addition, he teaches 4 graduate courses at Johns Hopkins University during summer and alternating semesters, and Biodiversity at the Maryland Institute College of Art.

Bill is author or co-author of 13 papers and continues to pursue his research interests in the fossil history and geology of rivers and wetlands as well as serpentine barrens in the central Maryland and southeastern Pennsylvania region. His graduate work dealt with the development of freshwater tidal wetlands along the Chesapeake Bay over the past 2,000 years. He uses analysis of macrofossils (seeds & leaves) from sediment cores to reconstruct past wetland vegetation, sedimentation rates, and disturbance, and applies the fossil record to understanding and addressing modern ecological and environmental problems. He also analyzes seeds gathered from archaeological excavations of prehistoric sites in Pennsylvania to determine the plants associated with prehistoric human populations. In the 1980s and early 1990s he conducted research in the Bahamas and the Caribbean collecting bird fossils while working in the Bird Division at the Smithsonian Institution in Washington, DC. This led to several studies of bird extinction, evolution, and biogeography of the Caribbean.