The plugging or rodding effect |
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As a non-vibrating tube penetrates sediment layers (1) of lower (white) and higher (gray) density, the tube may penetrate faster than sediment is collected (2) due to inner wall friction. Some of the sediments, especially softer layers, are pushed aside at the tube tip (2 and 3), resulting in thinner layers collected within the tube. When rodding or plugging occurs (4), the tube continues to penetrate, but no more sediment is collected. Vibration reduces the wall friction and increases the length of cores, and it improves the representative quality of the sediment column collected. |
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2 |
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4 |
From Weaver andSchultheiss, 1983 |
