RUMFORD — Eskers and other glacial formations will be the topic of a presentation May 20 hosted by the Rumford Historical Society.

Naturalist and environmental educator Bob Elliott will talk about the “Ancestral Androscoggin Esker” after the Society’s business meeting and elections for 2014-2015 officers. The meeting will begin 7 p.m. at the Rumford Municipal Building Auditorium.

The audience is invited to come early and look at the topographic maps of the esker and other features.

The presentation will begin with a brief overview of how Ice Age glaciers worked and a look at some local glacial landforms including kames, kettles and plunge-pit pot-holes.

Eskers are the remarkable gravel ridges, sometimes called a “whale’s back,” that dot the landscape for over 70 miles from Aziscohos through the Richardson Lakes, the Ellis River valley, Rumford Corner, Milton, Woodstock and down Rt. 26 through Paris, Oxford, Poland and on into Gray and Cumberland.

Elliott grew up on the Ellis River in North Rumford and is a retired University of Maine Associate Extension Professor with an MS degree in teaching, geology and ecology.

A field trip is also offered on Saturday, May 30, to explore local area features discussed on the 20th. It stars at 10 a.m. at the junction of Rts. 2 and 232 in Rumford Point.

Participants are advised to dress for the weather, wear good walking shoes and bring a bag lunch. They will return to Rumford Point by 2 p.m. The rain date is Saturday, June 6.