i 5 6 n a t u r a l h i s t o r y ,
depfeffioni forafinuch as the lodes oeüft owe their incitation to
diftind and pofteriour fubfidences produced by a caûfe’folûcfaswe
ft all ' by-and-by* enquire into, Another reafon of fome irrégularités,
is, tharnoTubfidence could equally affed all the adjacent parts
of To mixed a mafs as the inteftines of the earth are,1 nor all parts
moved fettle again in one direction ; from-the texture of1 the earth,
I fay, it could not happen, but that the inclinations would befeater
m;on^ place than in another, nay fome quite'ucontrary* to jbtfhers}
and the fed is agreeable to thé rationing ; for we fometimes find
two adjoining lodes of a quite oppofite inclination* viz. one under-
liès to the fouth, as C D, Fig. iv. Plate XVII. the/other, not
twenty fathoms: diftant, fhall underlye to the north, as Y Z, • tiH
both meet and unite at D, as in the mine called Huel-pufes in St.
Tuft. Such lodes will fometimes crofs each: other, as. Ç, D, a,
Y , D, Z, ibid, (as they do at Bartiny hill jn St. Juft) plain evidences
that they proceeded from fubfidènces on the different fidés
of the lodes, v iz. C D a from.a fubfidence at a Z b, ,and Y D Z
from a fubfidence at Z a c. Here „is alfo plain evidence that thefe
different fubfidences happened at different times, for one, lode de-
feends in full body through the other : when they orofs in filch, a
manner, it is not eafy to decide which of tfie two lodes was/fir ft
formed. Mr. Hutchinfon, in .his Tra<fts of the Gprnift lodes, page
19 and 20, thinks that thefe lodes which crofs, (thatis, run nprth
and fouth) and run in full body through the mdp:
run call and weft) were formed after the; main' lodes, which,
by cracking, gave way for the erofs-lodes to pafs through them, an
ingenious foppofition,. and moft likely in general to be true ; but much
will depend upon examining the inward ftruâure.ôf thefe lbdes^vif that
ftruâure is uniform throughout in each, and different from that of
the other, then Mr. Hutchinfon’s folution is right, and that which
is cracked muft have been prior to the other ; but if at the point
o f interfeétion, D, both lodes have nearly an equal mixture of the
fame feeders, ftone, clay, or ore, then were the fiffures inclined
probably, and became replete at one and the fame time, and filled
with one common matter.
s e c t . ix. But that there have been different fubfidences, and at different
t[meSj wiU frill be more convincing, from another remarkable polled
from frac- tion in which we fometimes find our Cornift lodes.
«redlodes. j n a m ;n e caued the North-Downs. (a confiderable mine of tin
and copper near Redruth) when they find the tin-lode quite worked
out at the bottom, and no farther appearance of a lode, either
dead or alive, (that is, impregnated or not) with or without walls ;
inftead of finking any farther, they drive acrofs, and at a final!
diftance
? Os F , . C O R N W A L L , 15%
«difta^eç/find a-part; of 4the jfeme natured tinrl©4® .a« they worked
before-,.' ,apd jn direâdpii-., Wherpthe parts of the fame lode
are .found thus fepapj^qd from each other,, the tinner’s exprefiion is,
foahthe lode is heaved or flirted .jt/and,.. as much may depend on the
reader’s clg,arly.appj$§hejfoing what, fohqre meant, let fis recur to the
Msplanatiqn of hgJdÿP.8.!; /Let A B 6Sjg. v. .Plate xyu.) he the lode
foft Wrought; thg, miners finkiqgs/till they çpmg'tq B, there find
|io /-mpre.lpde ; ^thewffolc.a li-ttlg 'farther in the direction A B, but
Jp- nû^urpofe gucffing..^aen frqM; t?hd'r ^pe^eB^ m_.like cafes:
that tfié ;lod© is heaved, or, rnb^feproperly fpeaking,, ftarted, they
fot/alone (the botÇorr)' ,and drivera ilev^ fâffage or drift to G;,
foere,,to- their jlpp^fort* fteyjfincJ|ajpart-pffopforruer lode C D ;
and having^wo^e.dit ,down to D,-s\vhere ft difappears, they- driv!|, ‘
^gain acçoîi.- fo,®, ,and fipWoifo it down .-to iffopr fes it goes.;,
in,d wj^en they find it no mfopimjthafc> dire^iran,| repqaf the feme,
feaïçfotp as good-p|irpofe as. before, fo that experienced, workmen
can teff.hearly at what diftance, and in what place,. the ftarted lode; .
fuge|y- tofoe found.-i .
» I n thejapds of Kelluz, in ^t,jErth, thq:Iqde is .flatted to. the. .
noçth fWenty-five fathoms ; butvtjfo is looked uppp a4/v©ry|extra-^
ordinary : the fame frajftures are obferved in the, cpal-mines, where,
ithere are^fometimes, fopugh rarely, three dippings, (as Dr. Plot, Stafik
■ fordfhirc, page* 1^0, ^fays) ahd the coal is laid to leap’: the c^liers • <
ïalfo frôm^spbrj^neé .know where to find it again.
Now in,this remarkable phenomenon, it firft appears, that A B,
C D, E F,(târe fo many feparate ? portions of ^th^!fa'me , lode ; for
they.confift of the feme pabula, the feme metal, and make.nea^lythe
(foufiae angle with the horizon, and abruptly and equally vanift ; being '
broken off, at B D Ç, at one and the fame mfouice ( nearly! they àp-,
pear agfoi; all irrefragable evidences that they are not differenUode^ *
but/^hj a diftind fruftum o î tire .feme lode.
j,Secondly^ That this lode "was formed before th^fiflure whiçh ;
contains it became indfoed and fiaâured. in this manner ; for B
was joined to C, and D to E, whereas now they are at a diftance.
Thirdly, That theidmuft havq been three fuccefiive different
ftocks which could create three fuch fradures.
Let us fee therefore whether the fubfidence the Jirata, the.
caufe before aftigned for the dippings of the lodes, will naturally
account alfo for this their very Angular disjointed ftate.
Firft then, from thefe and feverd other ^parent alterations in the skct.x.
bowels of the earth,, iç is highly probable, that tin? Jirata were n o t j ^ ^ '
only unfoqted, ftaken, and brought to fall, once only, or twice,
but lèverai times. Suppofing then the lode N F (Plate XVII. Fig. v.)
S f : M t i * in