Geology Reference
In-Depth Information
atoms, and a positively charged hydrogen ion. The hydrogen ions thus released, being
nothing more than protons, are small enough to travel easily amongst the much larger
chemical beings such as calcium, silicon and oxygen which hold the rock lattice tightly
together because of the way in which their positive and negative charges interact and
self-organise. Vast hordes of the tiny, positively charged hydrogen ions insinuate them-
selves into the rock. Ant-like, they pass through tiny gaps in the walls of the granite
castle and cluster around the negatively charged oxygen and silicon ions, neutralising
the electrical attractions that hold the rock together, so that what was once solid, impass-
able granite or basalt slowly dissolves like a wet sugar lump.
As the rock falls apart, carbon from the atmosphere, held fast in the bicarbonate ions,
combines with the newly liberated princesses, the calcium ions, merging in sacred chem-
ical marriage to become
calcium bicarbonate
, which loosely speaking is a water-soluble
form of chalk holding within it carbon dioxide removed from the air. There is a pre-
cise calculus here: each calcium ion weathered from the rock links up with two carbon
atoms from the atmosphere. The celebrants in these chemical marriages are so eager to
combine with each other that even a single rain drop falling on the bare surface of the
smallest pebble of basalt or granite is sufficient to initiate many chemical unions, as cal-
cium ions are at last released from their rocky prisons to conjoin with their ardent car-
bon suitors plucked from the atmosphere. This process, known to mainstream science as
calcium-silicate weathering,
removes carbon dioxide from the air, thereby cooling the
Earth.
The calcium bicarbonate solution gets flushed through the soil by rainfall, and even-
tually finds its way into rivers that carry it to the sea, where, if they are present, the coc-
colithophores precipitate it as solid chalk within their microscopic bodies. Other mar-
ine creatures also precipitate chalky shells and body armour from calcium bicarbon-
ate, amongst them crustaceans such as crabs and barnacles, and some molluscs, such
as clams, oysters and cuttlefish, whose lozenge-shaped chalk cuttlebones can often be
found washed up on beaches all over the world.
By precipitating chalk containing carbon dioxide stripped from the atmosphere, these
beings have a massive cooling effect on the entire planet. But it is the microscopic float-
ing chalk-forming phytoplankton that have provided the lion's share of this cooling ef-
fect over the last 80 million years or so. These tiny algae thrive over vast areas of the
cold oceans of the world. When they die, a chalky 'marine snow' settles on the bottom
of the sea, squeezing and squashing underlying accumulations of chalky skeletons into
solid chalk rock. In many parts of the world these chalk deposits can be seen above sea
level where they have been uplifted by the great movements of Gaia's crust. The famous
chalk cliffs known as the Seven Sisters in southern England are a marvellous example.
These cliffs are made almost entirely out of countless numbers of microscopic chalky
