This map of fossil footprint sites was printed as an oversize fold-out in Edward Hitchcock's major work on fossil footprints, Ichnology of New England, published in Boston in 1858. The map shows sites in the Massachusetts and Connecticut sections of the Connecticut River Valley. Although the river's northern half forms the border between Vermont and New Hampshire, no tracks are found there, because the sandstone formation in which the tracks and other fossil impressions are preserved ends just short of their borders with Massachusetts.