198 
NATURE FOR ITS OWN SAKE 
The earth's 
surface, 
Inequalities 
of surface, 
like, and if we could see it from a distance 
denuded of atmosphere, it would doubtless 
appear as a ball of water with patches of land 
hke large islands projecting above the surface. 
The greater part of the surface is on one level— 
that is to say, sea-level, which we accept as the 
standard. Above it there are elevations of 
land in points and ridges called mountains 
projecting upward some thirty thousand feet ; 
and below it there are depressions or holes in 
the sea extending down some thirty thousand 
feet. There are numerous exceptions to the 
rule of the sea-level marking land above and 
water below. Some of the plains and basins 
are below or above the sea-line. The margin 
of the Dead Sea lies thirteen hundred feet 
lower than that of the Mediterranean, and the 
great lake of Titicaca in the Andes, with an 
area of three thousand square miles, is nearly 
thirteen thousand feet above the Pacific. From 
Titicaca downward there are hundreds of 
bodies of fresh water conserved in great basins 
of the earth, which are as upland reservoirs to 
the sea itself. 
It is fortunate, indeed, that the earth has 
these upland reservoirs, fortunate that they 
are so equally distributed over the face of the 
