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tliofe channels confift, are /lopes, formed of loofe mate¬ 
rials fallen from the abrupt incumbent rocks ; and the 
uimfual bulk of the rapid water which now pit lies In that 
trough, caufes tjie bafe of tliofe Hopes to be attacked,- 
and fome of their materials to be carried away. There 
alfo he obferves, that all the trees now Handing on the 
upper parts of tliofe Jlopcs, muft tumble down fuccelfive- 
ly : for the looie grounds on which they have grown are 
undermined’; and the fteep fedtions' of tliofe grounds,’ 
though out of the reach of the torrents, are gradually 
deniolidied by the weather; thereby forming new Jlopcs 
under tliofe which are now decaying. It is efpecially 
from thole attacks of the water on loofe grounds, that it 
is mad c turbid-, but at the fame time lie obferves, that 
all the gravel, fo torn, fubfides as foon as the water comes 
to wider and lefs inclined parts of the channel, and that 
Hiere duft is carried down into the main flood. Laftly, 
in Ionic widened parts .of tliofe channels, he obferves, 
that tiie new Japes formed under the ruinous ones, are, 
even in that extraordinary weather, out of the reach of 
the torrents; and he may judge, that, when every other 
part of the bottom of thole troughs fhall be made wide 
enough to contain the fame quantity of water in a fixed 
bed, the fopes, covered again with Verdure, will remain 
unimpaired. Tliele fide torrents are the feeders of the 
main flood below, and the fame operations take place 
along the courfe- of every, one. of them, up to the re- 
nioteft rill, which is then alfo become a torrent. 
Our obferver has now entered on a diftindt /rc/d; or 
what I fliall call a diftindt fyjlem of grounds ; in which lie 
is fare, that, ever (ince the origin of our continents, all 
the rain-water that lias not immediately funk into the 
foil, muft have followed the fame courfe which it now 
purfues. He knows every part of that fet of grounds 
where the rain-water, by gently following oppolite decli¬ 
vities, divides itfelf between that fyjlem and the next 
grounds which feed other Rivers, Without any power of 
altering their original boundaries; and thence he traces 
in his mind, the ftrft gathered rills, the forms of their 
various channels, the places of their meeting, many (’pots 
where they fall abruptly, and many where they abate 
their courfe. Comparing, then, what lie has now ob- 
ferved of the effects of-a heavy and lading rain in that 
area, with its effects on other high grounds of equal ex¬ 
tent, but wliofe-declivities are regular and finooth, lie is 
ftruck with th ; e idea, that the ftrft fmall rills produced 
by the firft rain which fell on his fyfiem, could not have 
gathered, fo as to form, tliofe diftindt Jireams which lie has 
obferved, if that area had not previou/ly been interfedted 
by deep furrows tending to a lower place: for, rain-water, 
the fouree of all our continental waters, has not the power 
of driving heavy materials, till it has acquired bulk and 
velocity; and being once fettled in a channel, it cannot 
have any materials to drive along, except what may fall 
in its way. Now, the firft of thole circumftances muft 
arife from previou/ly wide and deep interfedtion of the 
ground, which alfo muft have a great declivity ; and the 
laft can only proceed from originally abrupt and decay¬ 
ing Hides of thole excavations. ’ Thence the prelect re¬ 
gular flare of lb many high grounds, which, though looje, 
arc not interfedted by chafms on any of their declivities : 
their furface was originally even, and the firft fmall rills 
of the rain-water, remaining ccnftantly feparate on that 
furface, have never acquired the power of digging daks 
and vales bordered with fteep (ides. Such is the firft ge¬ 
neral confequence derived by our obferver, both from 
his prefect remarks, and from all the fadts which they 
recall to his mind ; and on that previous point he con¬ 
cludes finally, that attributing the deep channels which 
interfedt his fyjlem of grounds, to the waters which are 
now feen pervading it, would be, taking for the eJfeEl of 
J'breams , the very cauje of alnioft every diftindt flream 
o-n our continents from their beginning ; namely, original 
hollow tracks. 
A firft fettled point in fuch inquiries is a firft ftep that 
R T fl. 
may lead farther. Our obferver now intends to examine, 
what has been the real elfiedt of running-waters, for-alter¬ 
ing the original form of his fyjlem ; and in that inquiry he 
firft compares the [ides of the vale with its lower ground. 
The inundation which he has obferved, notwitliftandino - 
its excels, did not reach the fopes of loofe materials, 
formed on the fides of that vale, under the vertical fcEtions 
of the upper grounds ; confequently, ih d frearns cannot 
have had any fnare in the form of tho le files \ they were 
originally fteep and crumbling, and their rubbilh has 
fucceftively formed tliofe fopes now covered with verdure: 
but fince tliofe fdes were originally abrupt, it is not in the 
nature of things- that they could then inclofe an horizon -. 
tal ground : fuch a chafm Was to have an irregular bot¬ 
tom, and muft have extended below the prefent level ; 
confequently, that horizontal ground, extending from hill 
to hill in the bottom of the vale, muft coafift of loofe 
materials carried down by the fide for rents. When our 
obferver forms that conjecture, the f ream is confined in 
its ufual bed, and much reduced by long dry weather : 
from that circumftance, a de<?p fedtion of the ground is- 
left uncovered on the banks of the ftream, and there his 
conjedture is confirmed ; for the upper part of that ground 
is mere fand, and the fragments of the fony frata which 
compofe the neighbouring hills, are feen in the lowed 
parts of the fedtion. 
That Jvccr/fton in the fediments compofing the horizontal 
ground of the vale, points out to our obferver a fort of 
chronometer ; by comparing that fuccelfive work of the 
f reams, with the ftate of til e fopes and f cep grounds, in the 
channels of the fide torrents-, which channels, hereafter, I 
fliall call dales. In a new furvey of tliofe, now quiet 
palfages of mere rills or rivulets, he finds firft, that many 
of them are furmounted, like a vale itfelf, by abrupt 
fedtions of the upper grounds ; and a greater proximity 
of their fides permitting an immediate comparifon be¬ 
tween them, he obferves, in many places, that the\xfrata- 
liave no correfpondence, either in dire ft ion , ftuation, or 
height: which is a new proof that all thefe chafms have 
been the effects of eonvulfions, antecedent to the prefent 
ftate of our continents. He alfo remarks charadteriftic 
differences between mod part of the dales and the vale; 
from which differences muft have refulted tiiofe which 
are obferved -in the effedts of running-waters. The vale 
was a wide and deep chafm ; the dales were narrow crevices, 
branching from that main one. The rubbifh, which, 
from the beginning, has fallen from the abrupt fides of 
the vale, has never been carried off by any external caufe; 
the bottom of that wide chafm became firft a fort of lake, 
along which the accumulated rubbifh remained undif- 
turbed ; but in the narrower and rapid dales, the firft 
fragments falling from the fteep fides, met together in the 
bottom of the trough ; and the torrents, whenever they 
were formed by heavy rains, drove them down to the 
vale ; where they were fpread by the united waters. None 
of tliofe fragments could remain in the rapid parts of the 
troughs, except wliat filled their hollow parts, and le¬ 
velled fiome wide f'paces; but every fragment carried 
farther, remained in the vale, where the water, from the 
extent of the f'pace, could not have any fenfible degree 
of rapidity. All the hollow parts of the bottom of the' 
vale were then to be filled and levelled, before any frag¬ 
ment could proceed farther: that operation, begun with 
fragments, has been finifhed with fand-, fince fand only is 
found at Home depth in the horizontal ground: confequent- 
ly, nothing but fand can ever have been carried out of 
that vale, by the waters palling through it. 
The prefent ftate of the dales affords inftances of the 
fame phenomenon, and points out its caufe. In going 
up forne of tliofe palfages, our obferver finds, at fuccef- 
fively higher levels, fume horizontal grounds, whole fcflions 
on the banks of the contradted rivulet, exhibit the fame 
order of materials that is obferved in the horizontal foil 
of the vale-, no large fragments are perceived in tliofe 
feci ions, but in the lowed parts j and confequently, none 
