Natural use materials that contrast the color and/or texture of the signaling area (rocks, brush, branches, stomped grass).

信号区域中颜色、纹理差异较大的材料（岩石，树林，树枝，践踏过的草地等）

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Qianceng stone is a kind of sedimentary rock, its texture into layered structure, in between layer and layer a layer of light grey rocks, stone into horizontal, one and weathered erosion of rock.

千层石是沉积岩的一种，其纹理成层状结构，在层与层之间夹一层浅灰岩石，石纹成横向，外形似久经风雨侵蚀的岩层。

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Qianceng stone is a kind of sedimentary rock, its texture into layered structure, in between layer and layer a layer of light grey rocks, stone into horizontal, one and weathered erosion of rock.

是沉积岩的一种，其纹理成层状结构，在层与层之间夹一层浅灰岩石，石纹成横向，外形似久经风雨侵蚀的岩层。

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