ox LAKE BASIXS. 
585 
mention many other instances^ but these are sufficient for my 
purpose. They shoTv the connecting link between seas and 
lakes^ and remind the reader that some of those lakes that 
are most different from the sea in the nature of their water 
contents and their geographical position_, and that are at 
present in the far interior of great continent s_, are still nothing 
more than portions of the great ocean accidentally cut off 
from communication. 
I mnst now request the attention of the reader to the out- 
lines in the accompanying’ plate, which show the forms of 
various lake basins. i\.mong them are outhnes of the Black 
Sea, the Caspian Sea, and the Dead Sea. Among them also 
are the Zuider Sea, in Holland ; a little salt lake called 
Tchokrak, in the Crimea; and an inlet on the coast of New 
Zealand. All these are more or less exceptions to the common 
and limited idea of lake basins : and it will be seen that they 
diflPer somewhat in form from most of the other lakes, many 
examples of which are as familiar as they are typical. What- 
ever may be the cause of the form of the oceanic basins, the 
same causes may be referred to as sufficient to explain these 
open lakes communicating, either now or formerly, with the 
sea. Thus the Mediterranean, the Black Sea, and the Sea of 
Azof, all novf connected by water passages, are yet perfectly 
distinct as basins. Each has its well-marked limits; each its 
peculiarities of depth and form of bottom ; each its peculiar 
condition of saltness ; each, above all, is distinctly marked 
by physical features connected with the geological structure 
of the district around ; and in this is the clue that may enable 
us to solve the problem of the origin of the phenomena, and 
the link that connects these basins with those of fresh-vrater 
lakes in other localities. I may add, that in these and many 
other like cases the smallest geological accident might sepa- 
rate them entirely from the open ocean, and reduce them to 
the state of lakes. 
The reader may find it useful to be reminded of the peculiar 
features just alluded to. A vast mountain chain exists in the 
old world, broken in various places by wide gaps, and pro- 
duced rather by innumerable points and centres of elevation, 
acting in a linear direction, than by any continuous force. 
This great chain is double. A northern line ranges from the 
Pyrenees through the Alps and Carpathians, the mountains of 
the Crimea and the Caucasus to the Altai group, and the 
chains that extend eastwards to the Pacific. A southern line 
commences with the Atlas mountains, and ranges eastwards 
to Arabia, and thence by the Himalayan chain to the south of 
China. It is between these two chains that the great inland 
Many of them have once communicated freely 
seas occur. 
