Page 19 - Curriculum Visions Dynamic Book. To close the book, close the tab.

Freezing point of water
0°C. The freezing point varies with the substances dissolved in the water. Seawater, for example, freezes at about -2°C, and very salty water may only freeze below -5 to -10°C. The freezing point of water is the same as the melting point of ice.
Fresh water
Water that contains less than
1g of dissolved salts per liter. Ninety-eight percent of fresh
liquid water is trapped in rocks as groundwater. Only 2% is held in rivers and lakes. Nevertheless, river waters are being replenished faster than groundwaters, so rivers represent a better sustainable water supply than groundwater.
G
Geyser
A pulsating source of hot water that jets upward from the ground to make a spectacular boiling fountain.
Geysers are produced when cold water seeps down into hot rocks and blocks already hot water from flowing to the surface.
When cold water flows down the same pipe that heated water
is trying to use to reach the surface, the cold water acts like a lid, trapping the hot water, so that it becomes hotter and hotter. Eventually,
 Geyser—Old Faithful geyser, Yellowstone National Park.
It erupts a fountain of water about once every 50 minutes, hence its name.
the pressure of the superheated water pushes the cold water out
of the pipe, shooting it upward as
a fountain. Once the pressure has been released, the geyser stops, and the cycle begins again.
Glacier
A river of ice. A valley glacier is a glacier that flows entirely within a valley. If a glacier comes out
of the mountains and spreads out onto a plain, it becomes part of an ice sheet. (See also: Crevasse; Ice crystals; Lake.)
 Glacier—This is the snout, or end, of a glacier. The streaks on the glaciers are broken rock that has fallen onto the surface of the ice and is being carried with it. It is called moraine.
Groin
A barrier placed in the bank of a river to prevent bank erosion and to keep water in the center of the river when water levels are low. Groins are also used on beaches that are liable to erosion. The groins are built out from the shore, trapping sand that would otherwise be washed from the beach. Groins
Groin
19