Four isolate barrier beds occurened usually in boundary surface of each internal architecture unit in channel sandbody, i. e. find bed, muddy pebble bed, plant clasts bed and diagenic bed.

道砂内部成的不同层界面上，通常存着4种隔挡层，即细粒物质隔挡层、泥砾隔挡层、植物碎屑隔挡层和成岩隔挡层。