WHERE'S THE WATER?

We live on the surface of the earth's crust, and what we see is only on the surface. Thus, we know that about 71% of the earth's surface is covered with water, and about 97% of that water is saline water in the oceans. So, fresh water--that which we drink and use in our lives--comprises only about 3% of all the water on the earth's surface.

Between the earth's crust and its core is a thick layer called the mantle. Now, according to a recent report, scientists believe that the mantle contains a huge amount of water deep in the earth.* It is suggested that this water is about 440 to 660 kilometers below the surface, perhaps where the upper mantle transitions to the molten lower mantle. Some have suggested that the mantle may contain as much water as all of the surface oceans, or even more.

Some of the mantle water may date back to early earth history. Another source may arise when tectonic plates collide, allowing ocean-soaked crust to seep into the mantle.

What does all this mantle water mean for us surface dwellers? Our wells penetrate only the earth's crust, so mantle water may be a wishful source of supply. On the other hand, mantle water may have other impacts, such as causing tectonic plates to move or producing volcanoes.

One thing may be sure: still waters run deep.

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* "Water Permeates Earth's Interior", Science Newa,
(July 12, 2014, p. 9)