108 Denudation of the Earih’s Surface. 
the earth’s surface! In like manner Mr. De Luc, when 
on his ‘¢ Geological Travels” in the West of England, had 
two instances of thts kind pointed out to him by practical 
Men, vol. ii. 218, and vol. iii. 27, but, whether from his 
Theory, offering no ready explanation, I will not inquire, 
these imporlant facts are passed by without comment. Mr. 
John Williams hints at them in his ‘* Mineral Kingdom,” 
2d Edit. 1. 96, but goes no further, and [ may say I think, 
that among the numerous theoretical writers since 1749, 
when by the publication of Mr. John Hutchinson’s works 
(written at the beginning of the century) for the first time 
probably, was pointed out (vol. xi. p. 338) this which ought 
to be a leading fact, in the formation of any subsequent 
Theory of the Earth, none of them have either attempted to 
explain it, nor had their writers the candour to notice it, as 
a phenomenon to which their particular Theory would not 
apply. . ; 
Similar remarks will nearly also apply to Denudation, or 
the stripping of tracts, on the Earth’s surface, both large and 
small, hill and dale, of vast loads of their superincumbent 
strata, which Dr. Wilham Richardson and myself have 
Jately investigated, more extensively and minutely, than 
formerly was done, see your xxxiild vol. p. 258, and xxxixth 
vol. p.26; which yet was distinctly pointed out, in the 
above Mr. Hutchinson’s works, vol. xii. 261, and was 
afterwards more fully treated of by his disciple The Rev. 
R. Catcott, in 1761, in his “ Treatise on the Deluge,” 
p- 159 and 163, and mentioned by Mr. Whiteburst in his 
“Inquiry” Ist Edit. p. 156 and 165, see also Derby Report 
p- 246. 
I proceed now to my Zigzag Fault, Rep. 1. p. 162 and 
165, whose form some have objected to, without being 
aware, that from most or all of its western salient angles, 
cross faults go off into the adjoining Coal district, generally 
an the direction or nearly, of one of the adjacent sides, and 
which cross faults are, in several instances, too well known 
to the Coal-masters whose works they intersect. 
Mr. Bakewel! in your xIth vol. p, 46, and in his Geology,. 
p- 283 Note, has carefully avoided entering at all into the 
evidence, of a demonstrative kind, or the facts capable of 
that kind of proof, which I originally offered, respecting 
the existence and course of this Fault through Derbyshire, 
particularly with regard to the Gritstone Rocks, Report i. 
169, and since, respecting others in Yorkshire, still more 
decisive, mentioned in your xxxixth volume, p. 101 and 
102, with respect to my 4th Grit Rock, (of Yorkshire pave 
ingstone), 
