Original Water

More than two thirds of Earth's surface is covered by water.

The Asteroid Belt

If Earth's primordial water was boiled off from the intense heat during planetary cooling, where did Earth's abundant water originate?

The origin of Earth’s water remains a mystery.

A prevailing hypothesis is that Earth's water came later from collisions with water-bearing comets or proto-planets from the outer reaches of the Asteroid Belt

Recent analysis of the composition of water sampled on comet 67P suggest Earth's water might not have come from cometary collisions (Life from Comet Collisions).

Scientists suggest that one key to solving the mystery of Earth's abundant water is found in the D/H ratio or the flavor of water. The D/H ratio is the proportion of Deuterium (symbol D) to Hydrogen (symbol H). The ratio of these two hydrogen isotopes might provide clues to the origin of Earth's water.

Deuterium is a form of hydrogen (i.e., hydrogen isotope) that has an additional neutron not present in common hydrogen. There are about 6,420 hydrogen atoms for every deuterium atom found in the world's oceans.

Deuterium can replace hydrogen in water molecules. The properties of D₂O differ from H₂O (common water). D₂O is called heavy water because it's 10.6% denser than H₂O. D₂O is also more viscous than H₂O.

The current opinion that science and poetry are opposed is a delusion. On the contrary science opens up realms of poetry where to the unscientific all is a blank. Those engaged in scientific researches constantly show us that they realize not less vividly, but more vividly, than others, the poetry of their subjects.
― Herbert Spencer, Education, Intellectual, Moral, and Physical (1861)

Analysis of the composition of water sampled on comet 67P, along with previous D/H analysis of other comets show a range of ratios generally containing higher amounts of deuterium than Earth.

Deuterium to Hydrogen Ratio in the Solar System

Source: ESA

Of the deuterium to hydrogen ratios detected in the solar system, the European Space Agency reports:

Of the 11 comets for which measurements have been made, it is only the Jupiter-family Comet 103P/Hartley 2 that was found to match the composition of Earth’s water.

The D/H ratio of water sampled on comet 67P is three times greater than that of Earth's oceans.

Scientists are are turning their attention to asteroids. Meteorites from asteroids in the Asteroid Belt have a closer match to the D/H ratio of water on Earth. Meteorites have a much lower water content than comets. However multiple serious of meteorite bombardments could have produced Earth's oceans.

Water does not resist. Water flows. When you plunge your hand into it, all you feel is a caress. Water is not a solid wall, it will not stop you. But water always goes where it wants to go, and nothing in the end can stand against it. Water is patient. Dripping water wears away a stone.
― Margaret Atwood, The Penelopiad

REFERENCES

• A Comet's Tale, shared on Google Plus by Brian Koberlein, 11 Dec 2014.
• Origin of Water on Earth, Wikipedia.
• Rosetta Fuels Debate on Origin of Earth's Oceans, European Space Agency, 10 December 2014.

Persistent Ice

Glacial ice is the largest freshwater reservoir on Earth. Glaciers are persistent bodies of ice that form where the accumulation of snow exceeds its ablation.

Glaciers account for a significant portion of the world's cryosphere.

ablation	The opposite of accumulation, ablation refers to processes that remove snow, ice, or water from a glacier (melting, evaporation, sublimation, calving, or wind erosion).
calving	Calving is the severing of chunks of ice at the terminus of a glacier.
cryosphere	Portions of Earth where water is in solid form (e.g., sea ice, lake ice, river ice, snow cover, glaciers, ice caps, ice sheets, and frozen ground).
sublimation	Sublimation is the conversion from the solid to the gaseous phase of water, without an intermediate liquid stage.

Calving at the terminus of the Perito Moreno Glacier in western Patagonia

Glaciers slowly deform and flow from the force of gravity.

The wintry clouds drop spangles on the mountains. If the thing occurred once in a century historians would chronicle and poets would sing of the event; but Nature, prodigal of beauty, rains down her hexagonal ice-stars year by year, forming layers yards in thickness. The summer sun thaws and partially consolidates the mass. Each winter's fall is covered by that of the ensuing one, and thus the snow layer of each year has to sustain an annually augmented weight. It is more and more compacted by the pressure, and ends by being converted into the ice of a true glacier, which stretches its frozen tongue far down beyond the limits of perpetual snow. The glaciers move, and through valleys they move like rivers.
— John Tyndall, 1861

Grinnell Glacier 1938

Grinnell Glacier 2009

Unlike seasonal snow cover, freshwater ice, or transient sea ice that lasts perhaps a few years, a water particle in a glacier can remain frozen 10-100,000 years longer.

A man who keeps company with glaciers comes to feel tolerably insignificant by and by.
— Mark Twain, 1880

99% of glacial ice resides within vast ice sheets cover the poles. Deep ice in East Antarctica might be approaching a million years in age.

The truth is, that those who have never entered upon scientific pursuits know not a tithe of the poetry by which they are surrounded.
— Herbert Spencer, 1889

REFERENCES

• A Tramp Abroad, Mark Twain, 1880.
• Education: Intellectual, Moral, and Physical, Herbert Spencer, 1889, 82-83.
• Glaciers, Wikipedia.
• The Glaciers of the Alps & Mountaineering, John Tyndall, 1861 (1911), 247.