46 Ain Essay on Rents. (Jory, 
retain their situations. But we have only to say, that the unsepa- 
rated rent is the older, and that the tabular masses in it were so 
sufficiently consolidated as to preserve their situations, when the 
separated rent was formed and filled, and the arrangement of these 
masses will evidently support this, equally as well as the other as- 
sertion: this reasoning will not, therefore, of zéself, decide whether 
is the older rent. When the unseparated rent is the larger, it is 
as old as, and probably older than, the separated rent. For, the 
formation of all rents commenced at their lowest extremities, and 
as the larger rent extends farther downwards than the smaller, if 
their respective dimensions be taken from one level, that part of 
the former which is below the lowest extremity of the latter must 
have been the soonest forming; and it is certain that the larger 
rent would commence in the stratum containing the lowest extre- 
mity of the smaller rent, as soon as this rent commenced in that 
stratum. Whether rent took the lead upwards we cannot tell with 
certainty: but that there has not been much difference im point of 
time between those unseparated rents which contain the first and 
second-~formed earthy tabular masses, and those separated rents 
which contain the earthy and metallic masses, is very probable ; 
because the first-formed earthy masses in both rents clearly point 
out the small degree of the matter’s solidity at the commencement 
of the formation of both these rents. One circumstance inclines 
me to suppose that the unseparated rent is the older; namely, the 
existence, in this rent near these junctions, of large metallic tabu- 
lar masses, which are similar to the metallic masses in the separated 
rent, and which are not found i other parts of the unseparated 
rent, except in very small quantities. For it is probable the hol- 
low places which contain these metallic masses were produced 
after those first-formed earthy masses near which they are situated, 
and that the metallic matter passed out of the separated rent into 
these hollow places in a fluid state. Now the metallic masses in 
the separated rent being cotemporary with the first-formed earthy 
tabular masses in it, it is clear that they were not produced as soon 
as the first-formed earthy tabular masses in the unseparated rent; 
hence, this is older than that rent. But in all junctions where the 
unseparated rent is'the smaller, it isthe newer rent; and then. its 
contents indicate its newness, 
There are four distinct examples of the horizontal junctions of 
bended-tabular rents, and eight angular junctions of the same rents; 
but as these junctions could not be described without reference to 
drawings, I have, for the present, omitted them. ‘The junctions 
also of bended-tabular with all other rents, | need not at present 
describe, as excellent descriptions of many of them will be found 
in Williams’ Mineral Kingdom, and.as the reader will have no dif- 
ficulty in referring all their phenomena to the cause whicli 1 have 
alreatly pointed out; namely, the unequal contraction of the earth’s 
Matter. 
June 7, 1815, 
