42G 
FORMATION OF MINERALS, CLAYS, ETC. 
admit of any amount of motion amongst themselves, large 
enough to let atoms of other matter circulate amongst and 
replace them; large enough to allow the combined atoms of 
hydrogen and oxygen as water to penetrate them. 
The mud deposited to-day at the mouth of the Rhine, the 
Ganges, or the Mississippi, is a mechanical mixture of lime 
and clay and water with grains of sand, fragments of wood 
and bone, marine and fresh water shells, particles of iron oxide, 
and the infinity of miscellanea that cannot fail to be brought 
together by fresh water running over a surface of land which 
is covered with vegetation and with animal life, and ultimately 
terminating its course and depositing its load where it meets 
the tidal wave of salt water. 
This mud deposited to-day will be buried to-morrow, and in 
the course of centuries will be covered up thickly, and remain 
permanently buried for a long time. 
What then will happen ? Do you suppose all will remain 
quiet ? Do you suppose that having entered nature’s great 
laboratory these materials will be left idle? Banish such a 
notion from your minds, and listen to what really will take 
place. 
First, decomposition commences, or advances if it had 
already commenced, in the organic matter. Gases will be 
evolved, these will affect the other compounds otherwise 
permanent; elective affinities will be called into play, and 
a general re-arrangement take place of all the particles until 
they attain a first state of temporary equilibrium. During 
all this time they are saturated with water, a heavy column 
of water presses upon them, and their temperature is more or 
less equable in proportion to the depth of the deposit. 
By degrees the water gets to a certain extent squeezed 
out of them, and they become solid instead of pulpy. The 
attraction of cohesion acts, and at last the wet pulpy mud 
either becomes changed into tough clay, or a sort of half- 
formed limestone is formed, or the mass remains loose sand. 
Then come into play certain movements of the earth’s 
surface. The ground sinks, the deposit continues, and at 
length the former mud becomes exposed at a steady, even 
temperature of some 200° or 300°, under great pressure of 
earth and water, to those magnetic currents which circulate 
through the earth. Then begins a fresh series of changes, 
crystallization starting at some atom of foreign matter. 
Some mud passes into tough clay, the lime-mud passes 
into beds of limestone, impurities and foreign substances 
accumulate together in bands, the shells become crystalline, 
and all are cemented together ; undecomposed wood tends to 
