184 
E A R T H. 
in which til-2 world would perifh.” On this there is 
jio queftion. “ But in the natural operations of tlie world, 
the land is perijbing continually ; and this is that which 
now vve want to underhand.” In this, no doubt, confifts 
the general queftion. “ Upon the one extremity of our 
land, there is no increafe, or there is no acceflton of any 
mineral fubftance. That place is the mountain-top, bn 
which nothing is obferved but continual decay .” This is 
much too generally exprelled : for there are many tops 
of mountains which do not decay, but, on the contrary, 
receive fome increafe by the accumulation of •:vegetable 
earth. However, to avoid particular queftions, I grant, 
that, upon the whole, the mountain-tops may be confidered 
as beiii^ in a ftate of decay. 
'The fragments of the mountain are removed in a gra¬ 
dual fucceflion, from the highef fituation to the lowefe. Being 
arrived at the Jbore, and having entered the dominion of the 
waves, in which they find perpetual agitation, thefe hard 
fragments, which had eluded the refolving powers natu¬ 
ral to the furface of the earth, are incapable of refilling 
the powers here employed for the dejlruchon of the land. 
By tile attrition of one hard body upon another, moving 
hones and rocky ftiores are mutually impaired. And that 
Jolid mafs, which of itfelf had potential (lability againft 
the violence of the waves, affords the inftruments of its 
own deferuBion ; and thus gives occafion to its actual in- 
/lability." This I do not grant in any refpeft. As to 
the manner of treating this fubjeft, it is determined by 
one of your own remarks. “In the defer uBion of the 
prefent earth, you fay, p. 297, we have a procefs that is 
performed ‘within the limits of our even obfervation: there¬ 
fore, in knowing the meafure of this operation, we fhall 
find the means of calculating what has pafled on a for¬ 
mer occafion, the JeJiruBion of former continents .” There¬ 
fore I fhall neither ufe, nor admit, any argument, which 
is not founded on immediate obfervation. 
You afiert in thefe few words, the deferuBion of our 
continents, in fetting out from the mountain-top. “ The 
fragments of the mountain are removed in a gradual (uc- 
ceflion, from the highefefeation to the lowefe. Here, furely, 
the procefs is within the limits of our obfervation. But in- 
flead of adducing prefent and oblervable fads, you have 
recourfe to ancient fuppofed ones. You mention the 
materials of which our continents are compofed ; and, taking 
for granted that thofe materials proceed from former con¬ 
tinents, you make that mere hypothefts the foundation of 
your proofs of the prefent deflrudion of ours. This will 
appear from the following examination: “Gravel, you 
fay firft, p. 289, forms u part of the materials which com- 
pofe our Jolid land. But gravel is no other than a collec¬ 
tion of the fragments of (olid ftones worn round, or hav¬ 
ing their regular form deftroyed by agitation in water, 
and the attrition upon each other, or upon fimilar hard 
bodies. Confequently,, in finding maffes of gravel in the 
compofition of our land, we muft conclude that there had ex- 
ifted a former land, on which there had been tranfacted 
certain operations of wind and water, fimilar to thofe which 
are natural to the globe at prefent, and by which new gravel is 
confeantly prepared .” Then, inverfely, if I demonftrate, 
by actual obfervation, that the operations of wind and water 
v.pon onr continents do not prepare any gravel for future 
ones ; I fhall have proved that the whole of your Theory 
is without foundation. 
“ Sand (you fay alfo) is the material which enters, per¬ 
haps, in greatefe quantity, the compofition of, our land. But 
fand is no other titan J'mallfragments of hard bodies, worn 
or rounded, more or lefs, by attrition. Confequently, the 
fame natural hifeory of the earth which is ir.vcjiigated from 
the maffes of gravel, is alfo applicable to thofe maifes of 
fund which we find forming fo large a portion of our land 
throughout all the earth.'" You agree here to a fa£t, which 
is veiy important in more than one refpeCt, viz. the im- 
menfe quantity of fand throughout all the furface of the 
earth. As for your conclufion, you will agree alfo, that 
A no gravel goes to the fa from our continents , the fand 
cannot proceed there front its attrition. But, previottfly, 
that definition of fund, which you here intend as a foun¬ 
dation for your argument, is in itfelf a mere hypothefis. 
In your Theory, you fometimes accumulate materials on 
the bottom of the f a, there to form ferata-, then you 
fpbak of railed ferata, vvhofe materials return to the feet. 
But before introducing thofe alternate operations, it was 
incumbent on you to explain the origin of thofe materials. 
For, you undertake to explain the general fact of the 
Jlratification of our continents-, a leading one in the former 
liiftory of the earth : and in that undertaking it anfwers. 
to nothing, to fuppofe, on whatever foundation, that new 
ferata are formed of antecedent ferata-, as it would be no¬ 
thing towards explaining the origin of vegetation, to fhew 
how a plant proceeds from another plant. You were then 
to explain, whence came the materials of which t-h ofrjl 
of all ferata were formed, before you could fay witli any 
foundation, that fand is no other than fmall fragments of for¬ 
mer hard ferata: for it may be, and I think it is, a fub¬ 
ftance which has formed ferata by precipitation in a liquid. 
You fee, then, that you ufe controvertible arguments s 
while, the procefs being within the limits of our obfervations , 
you ougli/t to have proved, that both gravel and fand are 
carried from our continents to the fea: which, on the con¬ 
trary, I (hall prove not to be cafe. 
You come next to clay-, and, as this fubftance bears a 
greater appearance of having been floated in water, if 
teems at firft more probable that our ferata of clay might 
have proceeded from the decay of former continents. I 
could fliew you, however, even by following direCtly the 
operations from which you fuppofe our day to have been 
formed, that its phenomena do not anfwer to that de- 
feription. But fucli a difquifition would be here uie- 
lefs, fince, what we have now to find out, and that by 
actual fad, is, whether or not ov.r continents are wearing ; 
away. 
You fpeak, laftly, of calcareousfubfiances ; and, continu¬ 
ing to follow your method of proving the exiftence of pre¬ 
fent operations by fuppofed pafi ones, you fay, firft, p. 2S8, 
“ We have already obferved, that all the ferata of the 
earth are compofed either from calcareous reliBs of fea 
animals, or from the collection of fuch materials as we 
find upon our /bores and, after having fo taken for grant¬ 
ed, that our calcareous ferata are the reliBs of fea animals, 
you enter into a long (peculation on vegetation and animal 
Ufe, to prove that our continents mufi wear away, to feed 
the prefent fea animals. But I have proved above, that 
our calcareous ferata cannot be fuppofed to be the relifts 
of fea animals and, by proving to you now, that our con¬ 
tinents do not decay, I fir a 11 anfwer, in the mod incontro¬ 
vertible manner, to the reft of your fpeculation. In that 
demonstration I (hall follow a plan that you have laid 
yourfelf. Before you entered into thefe fpeculative dif- 
quifitions, you had ufed an argument, a priori, from 
which you firft concluded, that it was neceflary that our 
continents fliould he deftroyed. There you trace opera¬ 
tions which ought to have been proved ; and I fhall fol¬ 
low the fame order, to prove that thofe operations do not 
exift: “ A folid body of land, you fay, p. 214, could 
not have anfwered the purpofe of a habitable world ; fora 
foil is neceflary to the growth of plants: and a foil (ift. 
Hyp.) is nothing but the materials collidedfrom the defer ac¬ 
tion of the folid laud. Therefore (2d. Hyp.) the furface of 
this land, inhabited by man, and covered with plants and 
animals, is made by nature to decay, in dilfolving from the 
hard and'com pact ftate in which it is found below the foils 
and this fail (3d. Hyp.) is neceffarily vjafhed away, by the 
continual circulation of the water running from the lum- 
mlts of the mountains towards the general receptacle of 
that fluid. (4th. Hyp.) The heights of our land are thus 
levelled with the Jhores : our fertile plains are formed from 
the ruins of the mountains 5 and thofe travelling materials 
are (till purfued by the moving water, and propelled along 
the inclined furface of the earth. (5th. Hyp.) Thefe 
moveable materials delivered into the fea, cannot for a 
