Abstract: Sand mud material brought by rivers accumulates at the mouth and then river mouth bar is formed. River mouth bar consists by sand and silt, classify is better and Quality is pure. Sand form is middle to thick layer. It develops wedge shaped cross bedding, shape prior product texture, horizontal texture. The formation of the mouth bar is a former product. Rhythm type is the counter rhythm which features the bottom of the sand body is fine, and the upper sand body is rough. The curve of the log is a funnel shape.