The winter world is evident in the grooved lines, called striations, etched in the bedrock of the mountains of New Hampshire, where mile-thick grindstones of ice advanced and retreated, scraping bare the scenery behind them. Long Island, Block Island, Cape Cod, Martha’s Vineyard, and Nantucket are all essentially dump heaps of rocks and sand where the ice sheets pushed south, sputtered and spewed their guts out onto the tundra.
