h the entire period of English history, from the landing of Julius
Caesar to the appearance of this present volume (to take two important
landmarks), is as one hour to a human lifetime, we quietly dig up the
salt to-day from that dry lake bottom and proceed to eat it with the
eggs laid by the hens this morning for this morning's breakfast, just as
though the one food-stuff were not a whit more ancient or more dignified
in nature than the other. Why, mammoth steak is really quite modern and
commonplace by the side of the salt in the salt-cellar that we treat so
cavalierly every day of our ephemeral existence.

The way salt got originally deposited in these great rock beds is very
well illustrated for us by the way it is still being deposited in the
evaporating waters of many inland seas. Every schoolboy knows of course
(though some persons who are no longer schoolboys may just possibly have
forgotten) that the Caspian is in reality only a little bit of the
Mediterranean, which has been cut off from the main sea by the gradual
elevation of the country between them. For many ages the intermediate
soil has been quite literally rising in the world; but to this day a
continuous chain of salt lakes and marshes runs between the Caspian and
the Black Sea, and does its best to keep alive the memory of the time
when they were both united in a single basin. All along this intervening
tract, once sea but now dry land, banks of shells belonging to kinds
still living in the Caspian and the Black Sea alike testify to the old
line of water communication. One fine morning (date unknown) the
intermediate belt began to rise up between them; the water was all
pushed off into the Caspian, but the shells remained to tell the tale
even unto this day.

Now, when a bit of the sea gets cut off in this way from the main ocean,
evaporation of its waters generally takes place rather faster than the
return supply of rain by rivers and lesser tributaries. In other words,
the inland sea or salt lake begins slowly to dry up. This is now just
happening in the Caspian, which is in fact a big pool in course of being
slowly evaporated. By-and-by a point is reached when the water can no
longer hold in solution the amount of salts of various sorts that it
originally contained. In the technical language of chemists and
physicists it begins to get supersaturated. Then the salts are thrown
down as a sediment at the bottom of the sea or lake, exactly as crust
fo