'When nature is on the point of creating stones it 
produces a kjnd of sticky paste, which, as it dries, 
forms itself into a solid mass together with what- 
ever it has enclosed there, which, however, it does 
not change into stone but preserves within it- 
self in the form in which it has found them! 

The lying interpreters of nature assert that mercury is a common 
factor in all the metals; they forget that nature varies its factors accord- 
ing to the variety of the things which it desires to produce in the world. 



c.a. 76 v. a 


The streams of rivers move different kinds of matter which are of 
varying degrees of gravity, and they are moved farther from their 
position in proportion as they are lighter, and will remain nearer to 
the bottom in proportion as they are heavier, and will be carried a 
greater distance when driven by water of greater power. 

But when this power ceases to be capable of subduing the resistance 
of the gravel this gravel becomes firm and checks the direct movement 
of the water which led it to this place. Then the water, as it strikes on 
the gravel which has been increased in this manner, leaps back cross- 
wise and strikes upon other spots to which it was unaccustomed, and 
takes away other deposits of soil down to their foundations. And so the 
places where first the said river used to pass are deserted and become 
silted up anew by a fresh deposit from the turbid waters, and these in 
due course become choked up in these same places. c.a. 77 v. b 

Of the rivers greatly swollen by the falling down of the mountains 
along their sides which bring about the formation of very great lakes 
at high altitudes: 

The avalanches from the mountains falling down upon their bases 




which have been worn away by the continuous currents <>! the rivers 
rushing precipitously at their Eeel with their swift waters, have closed 

up the mouths of the great valleys situated in the high places. 

These are the causes why the surface of the water is raised by the 
creation of lakes, and why new streams and rivers are formed in high 
places. C - A - 8 4 r - a 

The ebb and flow of the sea is continually moving the earth with all 
its elements away from the centre of the elements. This is proved by 
the first [chapter] of this [treatise], which states that the centre of the 
world takes count of that which is higher than it because no hollow 
lies deeper than it. The centre of the world is in itself immovable, but 
the place in which it is found is in continual movement towards differ- 
ent aspects. The centre of the world changes its position continually, 
and of these changes some have a slower movement than the others, for 
some changes occur every six hours and some take many thousand 

But that of six hours proceeds from the ebb and flow of the sea, the 
other comes from the wearing away of the mountains through the 
movements of the water produced by the rains and the continual 
course of the rivers. The site changes in its relation to the centre of the 
world and not the centre to the site, because this centre is immovable 
and its site is continually moving in a rectilinear movement, and such 
movement will never be curvilinear. c.a. 102 r. b 

The rains wear away more of the roots of the mountains than they 
do the summits for two reasons; and the first is that the percussion of 
the rain in falling from the same height is more powerful on the bases 
of the mountains than on their summits by my seventh [rule], which 
says that a heavy thing becomes so much swifter as it descends farther 
in the air, and as it becomes swifter so it becomes heavier. As therefore 
there is more space between the roots of the mountains and the cloud 
than between these clouds and the summit of the mountain, the rain, 
as has been said, is heavier and more powerful upon these roots of the 
mountains than on the summit of the same mountain, and so stage by 
stage its power to wear away is less as it has a less fall. 

The second reason is that the greater mass of water is that which 
descends from the centre of the mountain to its roots rather than from 



the summit of this mountain to the said centre; and so we have dis- 
charged our purpose. 

Valleys grow wider with the progress of time: their depth under- 
goes but little increase; because the rains bring as much soil to the 
valley almost as the river washes away, and in some pares more in 
others less. 

Very great rivers flow underground. 

The rivers make greater deposits of soil when near to populated 
districts than they do where there are no inhabitants. Because in such 
places the mountains and hills are being worked upon, and the rains 
wash away the soil that has been turned up more easily than the hard 
ground which is covered with weeds. 

The heights of mountains are more eternal and more enduring when 
they are covered with snow during the whole winter. c.a. 160 v. a 

In between water and stone in equal quantities are an almost infinite 
number of different grades of weight, that is there are as many varie- 
ties of the weights as there are of the thicknesses; so there will be pure 
water, then water with a very small quantity of earth in it, and then 
this is increased little by little until it forms mud, and then this mud 
becomes more solid, and at last it becomes solid earth, and then goes on 
to become like the hardest stone and is even transformed into the 

And this I say because I have to take away like things in order to 
press the water out of its vessels. 

Of the rising of the water to the mountains, which acts like water 
that rises up through the plants from the roots to the summits, as is 
seen in vines when they are cut; and as the blood works in all the 
animals so water does in the world, which is a living body. 

c.a. 367 v. b 

If the earth of the antipodes which sustains the ocean rose up and 
stood uncovered far out of this sea but being almost flat, how in 
process of time could mountains valleys and rocks with their different 
strata be created? 

The mud or sand from which the water drains off when they are left 



uncovered after the floods of the rivers supplies an answer to this 

The water which drained away from the land which the sea left, at 
the time when this earth raised itself up some distance above the sea, 
still remaining almost flat, commenced to make various channels 
through the lower parts of this plain, and beginning thus to hollow it 
out they would make a bed for the other waters round about; and in 
this way throughout the whole of their course they gained breadth and 
depth, their waters constantly increasing until all this water was 
drained away and these hollows became then the beds of torrents which 
take the floods of the rains. And so they will go on wearing away the 
sides of these rivers until the intervening banks become precipitous 
crags; and after the water has thus been drained away these hills com- 
mence to dry and to form stone in layers more or less thick according 
to the depth of the mud which the rivers deposited in the sea in their 
floods. f n v. 

Of creatures which have their bones on the outside, like cockles, 
snails, oysters, scallops, 'bouoli' and the like, which are of innumer- 
able kinds: 

When the floods of the rivers which were turbid with fine mud 
deposited this upon the creatures which dwelt beneath the waters near 
the ocean borders, these creatures became embedded in this mud, and 
finding themselves entirely covered under a great weight of mud they 
were forced to perish for lack of a supply of the creatures on which 
they were accustomed to feed. 

In course of time the level of the sea became lower, and as the salt 
water flowed away this mud became changed into stone; and such of 
these shells as had lost their inhabitants became filled up in their stead 
with mud; and consequently during the process of change of all the 
surrounding mud into stone, this mud also which was within the 
frames of the half-opened shells, since by the opening of the shell it 
was joined to the rest of the mud, became also itself changed into 
stone; and therefore all the frames of these shells were left between 
two petrified substances, namely that which surrounded them and that 
which they enclosed. 

These are still to be found in many places, and almost all the petri- 



fied shellfish in the rocks of the mountains still have their natural 
frame round them, and especially those which were of a sufficient age 
to be preserved by reason of their hardness, while the younger ones 
which were already in great part changed into chalk were penetrated 
by the viscous and petrifying moisture. f 79 r. 


All the creatures that have their bones within their skin, on being 
covered over by the mud from the inundations of rivers which have 
left their accustomed beds, are at once enclosed in a mould by this mud. 
And so in course of time as the channels of the rivers become lower 
these creatures being embedded and shut in within the mud, and the 
flesh and organs being worn away and only the bones remaining, and 
even these having lost their natural order of arrangement, they have 
fallen down into the base of the mould which has been formed by their 
impress; and as the mud becomes lifted above the level of the stream, 
the mud runs away so that it dries and becomes first a sticky paste and 
then changes into stone, enclosing whatsoever it finds within itself and 
itself filling up every cavity; and finding the hollow part of the mould 
formed by these creatures it percolates gradually through the tiny 
crevices in the earth through which the air that is within escapes away 
— that is laterally, for it cannot escape upwards since there the crevices 
are filled up by the moisture descending into the cavity, nor can it 
escape downwards because the moisture which has already fallen has 
closed up the crevices. There remain the openings at the side, whence 
this air, condensed and pressed down upon by the moisture which 
descends, escapes with the same slow rate of progress as that of the 
moisture which descends there; and this paste as it dries becomes 
stone, which is devoid of weight, and preserves the exact shapes of the 
creatures which have there made the mould, and encloses their bones 
within it. f 79 v. 


The creature that resides within the shell constructs its dwelling with 
joints and seams and roofing and the other various parts, just as man 



does in the house in which he dwells; and this creature expands 1 he- 
house and root gradually in proportion as its body increases and as it 
is attached to the sides of these shells. 

Consequently the brightness and smoothness which these shells pos- 
sess on the inner side is somewhat dulled at the point where they arc- 
attached to the creature that dwells there, and the hollow of it is 
roughened, ready to receive the knitting together of the muscles by 
means of which the creature draws itself in when it wishes to shut itself 
up within its house. 

When nature is on the point of creating stones it produces a kind of 
sticky paste, which as it dries, forms itself into a solid mass together 
with whatever it has enclosed there, which, however, it does not change 
into stone but preserves within itself in the form in which it has found 
them. This is why leaves are found whole within the rocks which are 
formed at the bases of the mountains, together with a mixture of dif- 
ferent kinds of things, just as they have been left there by the floods 
from the rivers which have occurred in the autumn seasons; and there 
the mud caused by the successive inundations has covered them over, 
and then this mud grows into one mass together with the aforesaid 
paste, and becomes changed into successive layers of stone which cor- 
respond with the layers of the mud. f. 80 r. 


And if you wish to say that the shells are produced by nature in 
these mountains by means of the influence of the stars, in what way 
will you show that this influence produces in the very same place shells 
of various sizes and varying in age, and of different kinds? 


And how will you explain to me the fact of the shingle being all 
stuck together and lying in layers at different altitudes upon the high 
mountains? For there there is to be found shingle from divers parts 
carried from various countries to the same spot by the rivers in their 
course; and this shingle is nothing but pieces of stone which have lost 
their sharp edges from having been rolled over and over for a long 


3 i 4 GEOLOGY 

time, and from the various blows and falls which they have met with 
during the passage of the waters which have brought them to this spot. 


And how will you account for the very great number of different 
kinds of leaves embedded in the high rocks of these mountains, and for 
the aliga, the seaweed, which is found lying intermingled with the 
shells and the sand ? 

And in the same way you will see all kinds of petrified things to- 
gether with ocean crabs, broken in pieces and separated and mixed with 
their shells. f 80 v. 

In every hollow at the summits of the mountains you will always 
find the folds of the strata of the rocks. b.m. 30 v.