Democratic messenger. [volume] (Snow Hill, Md.) 1869-1973, 1888-04-28
ANCIENT Lake, BONNEVILLE.
Great salt Lake the Largest Survivor Of
an Ancient Inland Sea.


nm Ancient Inland Sea.
The largest Of the ancient lakes ut
present known Is Lake bonneville, the
second in size has been narled Lake La
hontan. Lake Bonneville was situated
on the east border Of the Great Basin,
principally in Utah, and extended from
few miles north of tire Utah-Idaho
boundary $50 miles southwark. Il
flooded all the valley OF Great Salt lake,
together with the Sewer and Escalante
deserts in southern Utah. Il was 1875
miles broad and 1000 feet deep. where
Great Salt lake is now situated. The
site Of the temple mt Salt Lake City was
then submerged $50 feet.
Lake Bonneville overfowed northward
and became tributary to Snake river,
which flows into the Columbia. At va
rious stages its waves and currents
formed terraces and gravel bars on the
mountain slopes which confined 1t. These
still remain rs fresh and perfect rs when
they were formed, and are in part tho
records from which the geologist has
been able to determine the history Of the
ancient lake. We know that it rose with
many fluctuations until it had depth Of
about 900 feet, but did not overflow.
Then n change OF climate caused 1t TO
contract its borders, and possibly to be-
come completely dcsiccated. In tho
lower stages of this desiccation it was
broken into separate water bodies. which
must have been more or less saline.
Another great climatic change caused
the basin to bc refillcd to u higher level
than before and to overflow. The water
found an outlet ut the north end Of
Cache valley, Idaho, and, as we have
said, became tributary to the Columbia.
The lake continued TO overflow until the
waters had cut down their outlet $40
feet. During this period, unless there
were some peculiar conditions near the
point Of discharge, the lake must have
been fresh. The discharge Of the lake
was finally stopped by climatic change
which lowered its surface below the bot
tom of the outlet. and again the basin
became partly il not wholly dcsiccatcd.
This second low water period has con-
tinued to the present day, and Great Salt
and Sewer lakes are the representatives
OF ancient Bonneville.
The largest Of these representatives OF
the ancient sea is Great Salt lake. In
1850 it covered 1850 and in 1860 2,1GG
square miles. Its maximum depth is
about fifty feet and its mean depth ap-
proximatcly fifteen feet. These recent
changes in area are due to small varia-
tions in climate, similar in character TO
the changes which produced the great
expansions and contractions Of the lake
in ancient times. With change in vol
unie there is change in density; that is,
the strength of the brine increases with
decreased area, and decreases when tho
lake expands. In 1850 its waters con-
tanned about twenty-five parts, by weight,
Of saline matter in solution TO 100 parts
Of water. In 1869 the saline matter
had decreased to little less than Is and
in 1873 to little more than II rer cent.
This change in salinity was accompanied
by increased area.
The waters Of the ocean contain $40
per cent. of total salts in solution. Great
Salt lake, therefore. in 1850, was six
times rs saline rs the ocean. Like the
ocean, too, it holds many substances in
solution; the principal ones are common
salt. or so,liun chloride. and sodium sui
pliate; besides these there are small Ter
centagcs of potassium. magnesium, etc.
The influence Of temperature on the
solubility Of certain saline substances is
well illustrated by this dead sea of Utah.
In summer its waters are clear AMI
transparent, but as cold weath& comes
ON il becomes milky or opalcsccnt,
owing to the precipitation of sodium
sulphatc in an extremely fine condition.
In the depth Of winter, when the temper
aturc of the atmosphere above the lake
falls far below freezing, an immense
quantity of sodium sulphatc is precipi-
tatc,l and is thrown ashore by the waves
until thousands Of tons accumulate on
the beach. When the temperature rises,
the salt thus prccipitated is again dis
solved. This natural process Of frac.
tional crystallization proiuced by "a lower
ing Of temperature, is instructive. and
should suggest Ia these who are attempt
ing to manufacture salt in Utah prac-
tical method of treating the natural
brines In order TO obtain common salt
free from soiium sulphatc. Lake Sewer
Is also highly saline, and during the arid
season sometimes evaporates TO dryncss.
Israel c. Russell in Overland Monthly.