Changshou Bridge lies above the Black Dragon Pond, the bridge body is 23 meters long, spanning xixi, the bridge deck is shaped like a crescent moon, like a long rainbow lying wave, and the two sides are placed with arrow pole iron fences, painted red, and the green mountains and green waters shine, which looks exquisite and chic, and is particularly beautiful.
On the stone flat on the south side under the Longevity Bridge, at the top of Baizhang Cliff, there is a shallow white rock belt spanning the vertical river valley on both sides, as if a white stripe is embroidered on the edge of the cliff, because it is washed by the long-term flowing water, the surface is smooth as a mirror, and the color is bright and very eye-catching. If you are not careful to cross it, you will fall into the cliff and die in the valley, so it is called "Yin and Yang Realm".
The stone flat under the bridge is a light gray two-length granite, which belongs to the deep intrusive rock formed by magma condensation crystallization, and the lithology is relatively single, mainly composed of minerals such as oblique feldspar, micro-oblique feldspar, quartz and a small amount of black mica. Due to the relatively developed horizontal joints of this rock, after a long period of weathering and erosion and the erosion of the stream, such a wide and smooth large stone flat was formed.
"Yin and Yang Boundary" is actually a granite vein, light grayish white, 1 to 1.2 meters wide, the direction of the vein is 130 ° south to east, upright output in the two-long granite, its main mineral composition is oblique feldspar, quartz and micro-oblique feldspar, which is formed by the intrusion of granite solution along the fissure in the two-long granite during the process of mixed lithification.
This granite vein, and the boundary between the surrounding rock is very clear, the production is stable, the straight line extends, the contention is distinct, and it is located on the edge of the cliff of the East Baizhang Cliff, where the terrain is precipitous, the ancients regarded the rock vein as the dividing line between the yin and the yang, called the "yin and yang boundary", although there are some exaggerations, but it does not lose the vigilance effect on tourists, and at the same time, it also adds a bit of mysterious color to the scenery of the Longevity Bridge