The ground under Shinnecock Hills was left here by a glacier — sand, gravel and a rolling grade that never quite agrees to be flat. Marvin's Lawn Care reads that grade for a living, walking a mower across slopes where the turf thins on the crowns and thickens in the hollows. Late August, when the light turns amber by five and the lawns have taken a whole season of sun, is when steady tending shows. There is real pleasure in the last pass of the day: the stripe laid straight downhill, the trimmer line run tight against a fence post, the clippings blown off the walk. Southampton, Shinnecock Hills, Tuckahoe and Hampton Bays — a short territory, thoroughly known.