OF CORNWALL 143 
of the fiflure there is hard hone, on the other fometimes loofe clay ; 
the walls, generally fpeaking, are harder than the lode they inclofe, 
but fometimes fofter ; fometimes perpendicular, but much oftener 
declining fomewhat to the right or left as they defcend, but without 
any certain rule, and without any uniform relation to one another. 
FiiTures are not of equal breadth or depth : The courfe of Mures 
(efpecially great ones) is generally eaft and weft in Cornwall, yet 
in fome places have a north and fouth direction ; but in neither 
cafe do they exactly tend to the cardinal points : their courle, to 
whatever point they are diredted, is not in a ftraight line but wavy, 
full of little curves, alternately deviating from and recovering their 
chief direction ; the curves they make are generally greater at croff- 
ing a valley than otherwife; the larger fifliires have many letter 
veins branching out from them, which decreate, like the boughs 
of a tree, as they become farther diftant from the trunk, till they 
end in threads, aud are no more to be found ; thefe fubordinatc 
dependant veins join the mafter-fiflure at different angles. 
Let us now confider the origine of thefe fiftures, and the caute sect. iii, 
of their feveral properties. As to their origine, the learned are not Origine of 
agreed. Some u imagine them to be the chanels through which the fifluies ' 
waters retired at the time of the creation, that the ocean might be 
formed, and the dry-land appear; that where a large ftream chanced 
to force its way, the paflage became wide ; where only a petty cur- 
rent, the paftage was proportionably narrow : but to this may juftly 
be objected, that the walls of the fifliires are too hard in many places 
for the waters to have penetrated, in others too foft to have refifted 
the leaft impetuoftty of fuch a current. Their courfe does not at 
all agree with this theory ; for they run moftly eaft and weft, or 
towards the other cardinal points ; whereas, if they had been formed 
by waters retiring into the fea, they would thither generally tend ; 
but we find no fuch difpofttion, nor the leaft regard to the fea in 
their tendency. 
Others think them w fo many breaches of the Jlrata , made at 
the conclufion of the univerfal deluge ; whence it would follow, 
that there was neither fiflure nor lode before : but that the lode 
Was prior to the flood, the fhodes *, which have been dilperfed from 
the top of the lode by the flood, inconteftably fhew ; and that the 
fiflure muft be prior to the lode it bears, is as evident as that the 
cabinet muft have been made before the jewels could be inclofed 
and laid up in it. In fuch matters however it is more difficult to 
affign the true caufe, than to confute the falfe ones ; but in all 
8 Agricola de ortu, &c. lib. iii. pdge 39. v Woodward’s Nat. Hift. page 187. * Loofeftones. 
fuch 
