11. I'm wondering, during a glacial period , where does the ice actually come from? 12. During warmer post glacial periods , elephants and hippopotami roamed the valleys. 13. The glacial periods contributed large amounts of sediment to the trough. 14. During the glacial periods , the volcano most likely featured small glaciers. 15. The planet may be entering another glacial period by this time. 16. It arose during glacial periods and survived the subsequent warming of the local climate. 17. The pond was formed by the Wisconsin Ice Sheet during the last glacial period . 18. Her�ubrei?was formed beneath the icesheet that covered Iceland during the last glacial period . 19. During this last glacial period , there were several changes between glacier advance and retreat. 20. During glacial periods more of Zealandia becomes a terrestrial rather than a marine environment.
