why is the Yellow River yellow?

why is the Yellow River yellow? Yellow River flows into,the estuary is the Yellow River Yellow River前加不加the? The Yellow River is the second longest river in China. The yellow river is （) ( ) ( ) (）　（　）the Changjiang river in The Yellow River is the second（ ）river in China. The Yellow River is the s____ longest river in China. The Yellow River is China's the second longest river The yellow River is——than the Yangtze River The Yellow River is shorter than Changjiang River.The Changj is the chuangjiang river longest than the yellow river?