The Westport Historical Society will host a historian to speak about Connecticut's stone walls June 18 at 2 p.m. at the Betty and Ralph Sheffer Gallery at the society's headquarters, 25 Avery Place.

Robert Thorson is the author of "Stone by Stone: The Magnificent History in New England's Stone Walls," a regional bestseller that won the Connecticut Book Award for nonfiction.

He will present an overview of New England's historic stone walls, explaining why they are a signature landform of the region, and why they convey a sense of place. He will focus on southwestern Connecticut and will offer signed copies of his four books for purchase and inscription.

Thorson, who moved to New England in 1984, spent five years in California and Washington with the U.S. Geological Survey and contracted with international, federal, state and private agencies ranging from the Japanese Ministry of Culture to the National Geographic Society.

Thorson is a professor at the University of Connecticut's Department of Ecology and Evolutionary Biology and the Department of Anthropology, with additional commitments to the honors program and the Center for Integrated Geosciences.

Admission costs $10 for historical society members, $12 for non-members. Light refreshments will be served. Call 203-222-1424 for information.