GEOGRAPHICAL INTRODUCTION. 
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tainous, and may be aptly compared to a lofty chain, partly submerged in the 
sea ; — bays and channels occupying the position of valleys. The Eastern side 
almost exclusively consists of clay-slate ; the Western, of primary, and various 
plutonic formations. The mountains, from the water’s edge, to within a short dis- 
tance of the lower limit of perpetual snow, are everywhere (excepting on the ex- 
posed western shores) concealed by an impervious forest, the trees of which do 
not periodically shed their leaves. On the East coast, the outline of the land 
shows that tertiary formations, like those of Patagonia, extend south of the Strait 
of Magellan ; but with the exception of this part, it is rare to find even a 
small space of level ground ; and where such occurs, a thick bed of peat in- 
variably covers the surface. The climate is of that kind which has been deno- 
minated insular : the winters are far from being excessively cold, whilst the 
summers are gloomy, boisterous, and seldom cheered by the rays of the sun. 
In all seasons, a large quantity of rain falls. Hence, from the physical conditions 
of Tierra del Fuego, all the land animals must live either on the sea beach, (and in 
this class the Aborigines may be included) or within the humid and entangled 
forests. 
The Falkland Islands are situated in the same latitude as the Eastern 
entrance of the Strait of Magellan, and about 270 miles East of it. The 
climate is nearly the same as in Tierra del Fuego, but the surface of the land, 
instead of being as there, concealed by one great forest, does not support a single 
tree. We see on every side a withered and coarse herbage, with a few low bushes, 
which spring from the peaty soil of an undulating moorland. Scattered hills, 
and a central range of quartz rock, protrude through formations of clay-slate 
and sand-stone (belonging to the Silurian epoch,) which compose the lower 
country. 
The structure of the west coast of South America, from the Strait of Ma- 
gellan northward to latitude 38°, in its greater part, (as far north as Chiloe) is 
very similar to that of Tierra del Fuego. The climate likewise is similar, — being 
gloomy, boisterous, and extremely humid ; and, consequently, the land is con- 
cealed by an almost impenetrable forest. In the northern part of this region, the 
temperature of course is considerably higher than near the Strait of Magellan ; 
but nevertheless it is much less so, than might have been anticipated from so 
