china's two big mother rivers-the yellow river and the yangtze river.
, but you haven't noticed the shape of these two mother rivers.
the yangtze river like a right, from the source to the lijiang, yunnan, is basically a north-south direction.and lijiang tiger leaping gorge east, basically are things to go.the yangtze river is in the east of the river until it reaches the western pacific.
and the yellow river, as the children know, the yellow river is like a"a few"in the north of china.
why the morphology of the yellow river is so complex that the old saying goes:eighteen bend of the yellow river.why can't the yellow river form a straight line like the yangtze river?the zigzag pattern of the yellow river can't be found in the second place in the world.
this is the arrangement of"god".
:the yellow river was first appeared half a million years ago.at that time, the yellow river, like a little girl, was ashamed to answer.it's not big.there are lots of small lakes and rivers, not what it is.
:about 50,000 years ago, because of the intense movement of land, the original separate, scattered lakes were connected to the river section.
:the yellow river is also straight from the beginning, starting from zaling lake, ealing lake, and also a road east.
to qinghai, sichuan and gansu provinces, the yellow river suddenly has a thomas roundabout, then fold westward, a few hundred kilometers, almost back to the starting point.then it is a turn, then double is a shift, then 叒 is a turn, the shaanxi tongguan, eastward into bohai bay.
this has a lot to do with topography.the yellow river originated in the qinghai-tibet plateau.
here is dangerous, tens of millions of years to form.the power of the yellow river is not enough to change these mountains, but only to the point where it is weak.and in lanzhou, this is the loess plateau, where the soil is soft, and the upper reaches of the yellow river are relatively easy to impact, and can make a big gap.
, the yellow river should always be rushing out to the outer mongolia, and then it will turn its head to the east.this is because baryannur is a little bit further north, the same hard mongolian plateau.
the yellow river in power, is a hard, just have to to the east, near the togtoh suddenly turned south, the formation of shanxi and shaanxi geographical boundaries.why is that?this is the grand canyon.the yellow river has not yet been able to hit the grand canyon.
why did you get to the east of tongguan?again, the yellow river is not big enough.
:the yellow river says the yangtze river, why the yangtze river is a vertical one.
the history of the yangtze river is older than the yellow river.
:back in the triassic(200 million years ago), the upper reaches of the yangtze river were still vast oceans, and the middle and lower reaches of the yangtze river were all at the bottom of the sea.at the end of the triassic period, about 180 million years ago, the indo-china mountain movement was booming, and many plateaus appeared, including the kunlun mountains, hengduan mountains, the palazan mountains, and the yungui plateau.the qinghai-tibet plateau is also not idle, rising and rising, forming many fault zones, which are the most vertiginous grand canyon on the qinghai-tibet plateau and yungui plateau.by about 100 million years ago, the sichuan basin was slowly forming.
you must have discovered that the changjiang river is not just traveling through these mountain ranges.so, these new faults formed a trough of north-south direction, and the yangtze river was going down the trough to the end of the slot.
acuteness activity in the process of being formed because of the mountains, cause many lowland downfaulted basin or trough type hollow, gradually formed the lakes, and string together.but the ancient yangtze river did not flow to the east, but to the west, and eventually into the ancient mediterranean.this theory is made by famous geologist li siguang.
especially in the 40 million years ago, the qinghai-tibet plateau in the himalayan movement, under the influence of uplift is higher, it has formed the situation in which the west and low in.so you see, the yangtze river flows from the west to the lower east side.
nearest now, 3 million years ago, the himalayas and activities, the western higher, further widening the low altitude gap with the east.the yangtze river, from the high western side of the land, forms a huge impact, and it hits the ground in the east, and the bigger the collision.this is why the yangtze river is narrow in the gap between the qinghai-tibet plateau and the yunnan-guizhou plateau.
the yellow river and the yangtze river to form like this.it's all one reason--it's the terrain.the yellow river changed its passage in the hundreds of years between the jin dynasty and the qing dynasty xianfeng, trying to change it, indicating that the plains were basically incapable of preventing these great rivers from running wild.