supposing you 'd watched the slow accretion of snow over thousands of years as it was compressed and pushed over the deep rock until the glacier calved its icebergs into the sea , and you watched an iceberg drift out through the chilly waters , and you got to know its cargo of happy polar bears and seals as they looked forward to a brave new life in the other hemisphere where they say the ice floes are lined with crunchy penguins , and then wham !