... 96groundwater 67, 68, 75 , 78 superheated 34, 35water cycle 66– 67 waterfalls 71 waterspouts 91water table 67 water vapor 64, 65, 87 early atmosphere 17, 80water cycle 19, 66waves 47, 48, 82–83weather ... 34–35giant clam 103glaciers 24, 48, 67, 72 73 , 74 , 77 global warming 122gneiss 56Gobi Desert 111gold 40, 41, 116Gondwanaland 22gorges 70 71 , 78 Grand Canyon 71 granite 18, 19, 25, 43, 44, 46graphite ... one.TROPICS The hot regions to the north and south of the equator, between the Tropic of Cancer and the Tropic of Capricorn.TROPOSPHERE The lowest layer of the Earth s atmosphere.TSUNAMIA fast-moving...