Qinghai Lake originally was a lake connected
with sea. Because of the earth movement,
mountains raised and the lake became an
endorheic one.
It's believed that it was formed in 2million
years ago. In far ancient, it was part of
Mediterranean Sea. In the 3rd century, Alps
Movement made Qinghai-Tibet Plateau rise.
A large amount of sea fell down and formulated
Qinghai Lake. Some time later, another earth
movement made Riyue Mountain rise. As a
result, the only entrance of Qinghai Lake
was closed. The mineral material at the
bottom of the lake syncretized into the
water, which made it a salt-water lake.
There are about 30 rivers in the Lake District,
including Buha(Mongolian word, means urus)
River, Shaliu River, Ha'ergai River, Quanji
River, Ji'ermeng River and etc.
The perimeter of Qinghai Lake has changed
for dynasties. In Northern Wei Dynasty,
the perimeter was more than 1000km, while
in Tang Dynasty, it reduced to 400km and
in Qing Dynasty, it was only 350km. Nowadays,
the perimeter has shrunk to 30km. In
1908, the water level of Qinghai Lake
was measured by a Russian to be 3205m
and the lake surface is 4800 sq km. In
1970s, the two numbers reduced to 3195m
and 4473 sq km. In 1988, it was 3193.59m
and 4282 sq km. From 1955 to 1988, the
water level fell about 10cm annually.
Nowadays, the lake has 73.9 billion steres
of water, with length of 104km and width
of 62km. The depth point is 3.14m. The
average mineralization of water is 12.32
g/l and the salinity is 1.24%.
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