Relation of Secular Decay of Bods. — Tarr. 31 
far offered, though it is confessedly offered merel}' in the effort to 
suggest something plausible and is quite nithout facts in its sup- 
port. 
Strangely enough, origin by secular disintegration is not dis- 
cussed, though it may have been considered and found inapplica- 
ble for reasons not set forth in the treatise. To offer an expla- 
nation of a phenomenon simply upon the l)asis of the description 
of the phenomenon by others is extremely hazardous, and it is 
with much hesitation that 1 make the suggestion that the laterite 
may be the product of secular disintegration. So far as the de- 
scription goes, it may well be of this nature. It is an indestruct- 
ible clay of nearl}' uniform character sometimes grading down- 
ward insensibly into the rock below. As has been stated, resid- 
ual soils differ but little according to the nature of the source 
from which they have been derived, and the uniform character of 
the laterite may thus be accounted for as well as its occurrence on 
both basalt and gneiss. The description tallies remarkal)ly well 
with that of the residual soils of the southern states and Brazil. 
By removal into basins and valleys through subsequent denuda- 
tion a stratified product might well result, and, when carried to sea 
and deposited, a rock like the low level laterite might be expected. 
This would account for the apparent gradation of the "low level" 
laterite into the "high level"' form. 
Enough has been said of the occurrence of residual soils to show 
that they are extremely widespread. They occur wherever con- 
ditions have been favora])le. Given a moist climate in a region 
of slight topographic diversity and the conditions for the accumu- 
lation of a residual soil are brought about; and, if time is allowed 
such a soil will accumulate. In a mountainous region of tliverse 
topography, little soil can accumulate, for it is washed oft' as rap- 
idly as formed. In such regions the decay of rocks and the con- 
secjuent production ot sediments is probably more n^pid than in a 
region whose rocks are protected from frost and other sul)-aerial 
agents by a blanket of residual soil. Also, in arid regions, resid- 
ual soils do not readily form, partly because of the general ab- 
sence of humidity and vegetation, and parth' because the soils 
which do form are quickly removed, either by wind or water, on 
account of the absence of protective vegetation and the general 
aridity. 
