Hartshorn, Joseph H., Gerald Martin Richmond, and David S Fullerton. <i>Quaternary Geologic Map of the Boston 4⁰ x 6⁰ Quadrangle, United States and Canada.</i> Version 1.1, posted Aug. 2006. Reston, Va.: U.S. Dept. of the Interior, U.S. Geological Survey, 2006.