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Several other castings with precipitated chalk placed on their
summits were left to the natural action of the rain。 In one case；
after rain which was not heavy； the casting was longitudinally
streaked with white。 In two other cases the surface of the ground
was rendered somewhat white for a distance of one inch from the
casting； and some soil collected at a distance of 2。5 inches； where
the slope was 7 degrees； effervesced slightly when placed in acid。
After one or two weeks； the chalk was wholly or almost wholly
washed away from all the castings on which it had been placed； and
these had recovered their natural colour。
It may be here remarked that after very heavy rain shallow pools
may be seen on level or nearly level fields； where the soil is not
very porous； and the water in them is often slightly muddy； when
such little pools have dried； the leaves and blades of grass at
their bottoms are generally coated with a thin layer of mud。 This
mud I believe is derived in large part from recently ejected
castings。
Dr。 King informs me that the majority of the before described
gigantic castings； which he found on a fully exposed； bare；
gravelly knoll on the Nilgiri Mountains in India； had been more or
less weathered by the previous north…east monsoon； and most of them
presented a subsided appearance。 The worms here eject their
castings only during the rainy season； and at the time of Dr。
King's visit no rain had fallen for 110 days。 He carefully
examined the ground between the place where these huge castings
lay； and a little watercourse at the base of the knoll； and nowhere
was there any accumulation of fine earth； such as would necessarily
have been left by the disintegration of the castings if they had
not been wholly removed。 He therefore has no hesitation in
asserting that the whole of these huge castings are annually washed
during the two monsoons （when about 100 inches of rain fall） into
the little water…course； and thence into the plains lying below at
a depth of 3000 or 4000 feet。
Castings ejected before or during dry weather become hard；
sometimes surprisingly hard； from the particles of earth having
been cemented together by the intestinal secretions。 Frost seems
to be less effective in their disintegration than might have been
expected。 Nevertheless they readily disintegrate into small
pellets； after being alternately moistened with rain and again
dried。 Those which have flowed during rain down a slope；
disintegrate in the same manner。 Such pellets often roll a little
down any sloping surface； their descent being sometimes much aided
by the wind。 The whole bottom of a broad dry ditch in my grounds；
where there were very few fresh castings； was completely covered
with these pellets or disintegrated castings； which had rolled down
the steep sides； inclined at an angle of 27 degrees。
Near Nice； in places where the great cylindrical castings；
previously described； abound； the soil consists of very fine
arenaceo…calcareous loam； and Dr。 King informs me that these
castings are extremely liable to crumble during dry weather into
small fragments； which are soon acted on by rain； and then sink
down so as to be no longer distinguishable from the surrounding
soil。 He sent me a mass of such disintegrated castings； collected
on the top of a bank； where none could have rolled down from above。
They must have been ejected within the previous five or six months；
but they now consisted of more or less rounded fragments of all
sizes； from 0。75 of an inch in diameter to minute grains and mere
dust。 Dr。 King witnessed the crumbling process whilst drying some
perfect castings； which he afterwards sent me。 Mr。 Scott also
remarks on the crumbling of the castings near Calcutta and on the
mountains of Sikkim during the hot and dry season。
When the castings near Nice had been ejected on an inclined
surface； the disintegrated fragments rolled downwards； without
losing their distinctive shape； and in some places could 〃be
collected in basketfuls。〃 Dr。 King observed a striking instance of
this fact on the Corniche road； where a drain； about 2。5 feet wide
and 9 inches deep； had been made to catch the surface drainage from
the adjoining hill…side。 The bottom of this drain was covered for
a distance of several hundred yards； to a depth of from 1。5 to 3
inches； by a layer of broken castings； still retaining their
characteristic shape。 Nearly all these innumerable fragments had
rolled down from above； for extremely few castings had been ejected
in the drain itself。 The hill…side was steep； but varied much in
inclination； which Dr。 King estimated at from 30 degrees to 60
degrees with the horizon。 He climbed up the slope； and 〃found
every here and there little embankments； formed by fragments of the
castings that had been arrested in their downward progress by
irregularities of the surface； by stones； twigs； &c。 One little
group of plants of Anemone hortensis had acted in this manner； and
quite a small bank of soil had collected round it。 Much of this
soil had crumbled down； but a great deal of it still retained the
form of castings。〃 Dr。 King dug up this plant； and was struck with
the thickness of the soil which must have recently accumulated over
the crown of the rhizoma； as shown by the length of the bleached
petioles； in comparison with those of other plants of the same
kind； where there had been no such accumulation。 The earth thus
accumulated had no doubt been secured （as I have everywhere seen）
by the smaller roots of the plants。 After describing this and
other analogous cases； Dr。 King concludes： 〃I can have no doubt
that worms help greatly in the process of denudation。〃
Ledges of earth on steep hill…sides。Little horizontal ledges； one
above another； have been observed on steep grassy slopes in many
parts of the world。 The formation has been attributed to animals
travelling repeatedly along the slope in the same horizontal lines
while grazing； and that they do thus move and use the ledges is
certain； but Professor Henslow （a most careful observer） told Sir
J。 Hooker that he was convinced that this was not the sole cause of
their formation。 Sir J。 Hooker saw such ledges on the Himalayan
and Atlas ranges； where there were no domesticated animals and not
many wild ones； but these latter would； it is probable； use the
ledges at night while grazing like our domesticated animals。 A
friend observed for me the ledges on the Alps of Switzerland； and
states that they ran at 3 or 4 ft。 one above the other； and were
about a foot in breadth。 They had been deeply pitted by the feet
of grazing cows。 Similar ledges were observed by the same friend
on our Chalk downs； and on an old talus of chalk…fragments （thrown
out of a quarry） which had become clothed with turf。
My son Francis examined a Chalk escarpment near Lewes； and here on
a part which was very steep； sloping at 40 degrees with the
horizon； about 30 flat ledges extended horizontally for more than
100 yards； at an average distance of about 20 inches； one ben