1. Map showing morphometry, bathymetry, and soft-sediment thickness of Plow Shop Pond and Grove Pond, Ayer, Massachusetts Yale Public content 1999. 2009-02-24T17:47:14Z. 2021-10-01T21:33:27Z. Geological Survey (U.S.). The Survey. English. Public. Massachusetts, Ayer Region, and Middlesex County.